The Diamondbacks Have Wilted in the Heat of a Playoff Race

David Kohl-USA TODAY Sports

In an attempt to arrest a slide that began in early July, the Diamondbacks were busy in the run-up to the August 1 trade deadline, but so far, their moves haven’t been enough to turn things around. In fact, they have yet to win a game in August, having finished a seven-game road trip by losing six in a row to the Giants and Twins. On Sunday, their highest-profile deadline addition, former Mariners closer Paul Sewald, failed to retire a batter in his first save opportunity since the trade. Instead, he served up a game-tying homer to Max Kepler on his first pitch and then, after a walk, a two-run walk-off homer to Matt Wallner. Ouch.

After spending the majority of the first half leading the NL West, the Diamondbacks have slipped to sixth in the NL Wild Card race, 1.5 games behind the Cubs and Reds, who are tied for the third spot. Their trend is actually worse than that. Since winning on July 1 to lift their record to 50-34 and restore their NL West lead to three games, the Snakes have gone 7-22 (.241). That’s worse than the A’s (9-19, .321) or any other team in the majors. It’s not as though they’ve been particularly jobbed in the process; their Pythagenpat record is the majors’ worst in that span as well:

Worst Record Since Games of July 1
Team W L W-L% RS RA PythW-L%
Diamondbacks 7 22 .241 103 161 .306
White Sox 9 19 .321 110 145 .376
Athletics 9 18 .333 103 138 .369
Marlins 10 19 .345 122 140 .437
Pirates 11 18 .379 107 151 .347
Rays 11 17 .393 111 122 .457
Royals 12 18 .400 130 153 .426
Yankees 12 17 .414 113 145 .388
Rockies 11 15 .423 108 129 .419
Angels 12 16 .429 135 154 .440
Tigers 13 16 .448 121 145 .418
Mets 13 15 .464 112 131 .429
Cleveland 14 16 .467 129 123 .522
Reds 15 16 .484 139 147 .474
Cardinals 15 16 .484 147 147 .500
Giants 15 14 .517 98 114 .431
Brewers 16 14 .533 132 121 .540
Nationals 16 14 .533 148 155 .479
Rangers 16 13 .552 157 145 .536
Braves 15 12 .556 155 128 .587
Red Sox 15 12 .556 134 120 .550
Phillies 17 13 .567 138 127 .538
Twins 17 12 .586 149 134 .548
Padres 17 12 .586 157 112 .650
Blue Jays 18 11 .621 141 105 .632
Astros 19 11 .633 154 144 .531
Dodgers 18 10 .643 175 128 .639
Cubs 20 11 .645 205 156 .622
Mariners 21 10 .677 146 115 .607
Orioles 22 9 .710 165 109 .681
SOURCE: Baseball-Reference

To be fair, the Diamondbacks weren’t expected to be a powerhouse this year; after going 74-88 last year, they projected for 78.4 wins via our preseason Playoff Odds. In a slow-starting NL West, they took over a share of first place for the first time on April 8, when they were 5-4, and finished the month 16-13, which was good enough to tie for first. Despite going 17-10 in May, they didn’t get a share of first place again until June 1, but they spent that entire month atop the division — most of it with sole possession of first place — while going 16-11.

It was around that time that Corbin Carroll’s season started taking an unfortunate turn. On June 29 — the same day he was named as a starter for the National League in the upcoming All-Star Game — the 22-year-old outfielder left a 6-1 loss to the Rays after four innings, having experienced soreness in his right shoulder during a third-inning plate appearance. It was the same shoulder on which he’d undergone surgery to repair a torn labrum in 2021, which cost him nearly the entire season. In the wake of his removal from the game, he underwent strength testing, which showed that his shoulder was strong and stable, but the Diamondbacks gave him a breather, limiting him to a single pitch-hitting appearance over the next three days. After returning to the lineup, he played just three more games before leaving the team’s July 6 tilt against the Mets in the seventh inning, once again in pain. “I took a swing, and I felt a shift in my shoulder, shocking, tingling sensation go down my arm and then my hand go numb,” he told reporters. “I was just holding it thinking it came out of the socket, pretty much thought that the season was over.”

Despite his initial concerns, Carroll had not experienced a dislocation, and his MRI came back clean. He was back in the lineup the next day, and while he’s certainly had his moments since then — and hasn’t missed a game — his production and quality of contact are down considerably since the first incident:

Corbin Carroll Before and After Shoulder Scare
Period PA HR AVG OBP SLG wRC+ EV Barrel% Hard-Hit%
Through June 29 323 17 .290 .366 .559 146 90.8 9.4% 42.9%
Since July 1 119 4 .240 .336 .420 105 88.1 5.1% 35.4%

Note that with two hits and two walks on Sunday, Carroll raised his post-July 1 wRC+ nine points; he was at 96 previously. Along the way, his swinging strike rate has spiked from 8.4% to 12.4%, and his chase rate from 28.8% to 32.6%, though his strikeout rate has barely budged, from 19.8% to 20.1%.

Maybe Carroll’s downturn in production is related to his shoulder woes, maybe it’s just the league adjusting to a player who looked like an MVP candidate early in the season, or maybe it’s just regression, more on which below. One way or another, it’s been poorly timed, in part because he’s not the only Diamondback who has tailed off in recent weeks:

Diamondbacks Hitters Through June and Since
Gabriel Moreno 216 .261 .296 .342 70 28 .348 .464 .522 173 103
Christian Walker 336 .278 .343 .522 128 126 .222 .325 .481 113 -15
Corbin Carroll 323 .290 .366 .559 146 119 .240 .336 .420 105 -41
Ketel Marte 339 .291 .372 .514 137 121 .261 .322 .450 104 -33
Alek Thomas 164 .222 .268 .366 68 79 .256 .266 .487 96 28
Jake McCarthy 186 .247 .319 .355 84 89 .273 .364 .325 94 10
Dominic Fletcher 89 .305 .345 .463 115 13 .273 .385 .273 92 -23
Lourdes Gurriel Jr. 296 .274 .324 .496 118 116 .218 .259 .418 78 -40
Emmanuel Rivera 152 .306 .329 .396 94 82 .205 .293 .356 77 -17
Geraldo Perdomo 250 .285 .388 .435 125 106 .225 .324 .292 73 -52
Carson Kelly 33 .200 .242 .233 27 49 .196 .245 .283 41 14
Evan Longoria 144 .254 .313 .562 128 34 .167 .265 .233 40 -88
Nick Ahmed 124 .231 .274 .342 65 37 .200 .243 .257 34 -31
Jose Herrera 68 .255 .344 .327 87 22 .100 .182 .100 -20 -107
Josh Rojas 210 .235 .301 .306 66 6 .000 .000 .000 -100 -166
Pavin Smith 217 .190 .310 .332 79
First set of statistics (PA, AVG, OBP, SLG, wRC+) through June 30, second set through August 6.
Dif = wRC+ in second set relative to first set.

Just four Diamondbacks have a 100 wRC+ or better since the start of July, one of them a catcher (Moreno) who has been limited to 11 of the team’s first 29 games in that span and is now sidelined by left shoulder inflammation. Moreno, Thomas, and McCarthy are the only three players with a higher wRC+ since the start of July than before, and they’re still below average offensively overall. Deadline additions Tommy Pham (from the Mets) and Jace Peterson (from the A’s) have yet to make an impact, going a combined 4-for-30, all singles.

Meanwhile, note that not only has Carroll fallen off steeply but so have Gurriel and Perdomo, both of whom joined him on the NL All-Star squad but might as well be on the side of a milk carton these days. Setting the narrative of Carroll’s shoulder injury to the side for a moment, this is striking:

Diamondbacks All-Stars Regressing
Player Period PA AVG xBA SLG xSLG wOBA xwOBA wOBA-xwOBA
Corbin Carroll Through June 30 322 .290 .258 .559 .450 .391 .345 .046
Since July 1 119 .240 .265 .420 .439 .330 .350 -.020
Lourdes Gurriel Jr. Through June 30 296 .274 .252 .496 .424 .350 .319 .031
Since July 1 116 .218 .256 .418 .483 .290 .333 -.043
Gerardo Perdomo Through June 30 249 .285 .208 .435 .279 .360 .280 .080
Since July 1 106 .225 .218 .292 .296 .283 .284 -.001

All three players hit well above their Statcast expected stats through the end of June, particularly Perdomo, a slappy switch-hitter who doesn’t hit the ball hard at all; his season barrel rate is 1.2%, his hard-hit rate 19.9%. Then it’s as though the Regression Monster showed up and took a bite — each of these three players has seen about a 75-point swing in their wOBA-xwOBA differential.

Overall, the Diamondbacks hit .263/.330/.437 through the end of June, ranking fifth in the majors in scoring (5.11 runs per game) and seventh in wRC+ (106). Since then, they’ve hit just .227/.302/.373 while ranking 29th in scoring (3.44 runs per game) and 26th in wRC+ (83). Their performance against every major pitch type except changeups has fallen off by at least 50 points of SLG and 25 points of wOBA:

Diamondbacks Hitters vs. Pitch Types
Through June 30 938 .287 .262 .491 .450 .373 .354
Since July 1 344 .254 .239 .401 .404 .348 .344
Through June 30 584 .306 .287 .460 .423 .363 .347
Since July 1 200 .266 .276 .380 .413 .311 .329
Slider/Sweeper PA AVG xBA SLG xSLG wOBA xwOBA
Through June 30 691 .221 .201 .411 .350 .295 .273
Since July 1 222 .174 .204 .324 .314 .237 .251
Through June 30 278 .248 .220 .420 .347 .302 .267
Since July 1 92 .214 .223 .369 .414 .274 .295
Through June 30 341 .256 .262 .394 .385 .297 .299
Since July 1 133 .252 .235 .433 .346 .306 .270
SOURCE: Baseball Savant

Yikes. They were punishing four-seam fastballs earlier in the season, but that’s stopped, and they’ve particularly gotten eaten alive by sliders and sweepers lately. What’s especially strange is the general downward trend of their more recent numbers despite the weather getting even warmer, which tends to increase offense. Of course, it’s as hot as the surface of Mercury in Arizona, so maybe the Diamondbacks have just wilted in the heat.

That does seem to be true with the team’s pitching, particularly the bullpen:

Diamondbacks Pitchers Wilting in the Heat
Rotation Through June 30 443.1 20.3% 8.7% 1.14 4.65 4.33 6.3
Rotation Since July 1 162.2 20.8% 6.2% 1.77 4.92 4.99 1.1
Bullpen Through June 30 295.0 24.1% 9.1% 1.07 4.00 4.03 2.6
Bullpen Since July 1 96.1 23.6% 11.2% 1.87 6.35 5.57 -0.9

Good gravy. In writing about the Sewald trade — which sent Rojas and prospects Dominic Canzone and Ryan Bliss to Seattle — I noted that manager Torey Lovullo had been working with a matchup-based closer-by-committee system involving righties Miguel Castro, Kevin Ginkel and Scott McGough and lefty Andrew Chafin. However, I did not drill down to see just how bad things had gotten for them in the recent past. Using the July 1 cutoff again, with full awareness of the small samples in play, Ginkel has pitched well (0.75 ERA, 2.35 FIP in 12 innings), but the other three had been torched, with Castro (6.00 ERA and 6.60 FIP in 12 IP) the “best” of them, though he had stopped getting ninth-inning save chances, and Chafin (9.95 ERA and 5.63 FIP in 6.1 IP) and McGough (8.76 ERA and 6.91 FIP in 12.1 IP) utterly terrible. Chafin had two blown ninth-inning saves that led to losses in that span; he’s now a Brewer.

As for the rotation, it’s been pretty unstable, with Zac Gallen and rookie Ryne Nelson the only real constants, and both of them experiencing fall-offs since the start of July. Gallen pitched to a 3.02 ERA and 2.73 FIP in 104.1 innings through June, making his first All-Star team, but has yielded a 4.17 ERA and 4.12 FIP in 45.1 innings since, with his home run rate increasing from 0.6 per nine to 1.6. Nelson went from a 4.97 ERA and 4.44 FIP to a 5.59 ERA and 6.19 FIP, not that it should have been too surprising given his double-digit barrel rate even in the “good” times. Merrill Kelly, the team’s second-best starter, missed four weeks (most of July) due to a blood clot in his right calf but has been solid when available. Tommy Henry showed some improvement before being sidelined last week due to elbow inflammation. Brandon Pfaadt has been getting better results since being recalled on July 22 than prior, though his overall ERA of 7.11 in 44.1 innings is pretty damning. Also sporting an unsightly ERA (7.38) is Zach Davies, who has been dreadful on both sides of the divide while missing time with oblique and back injuries. Slade Cecconi, the team’s 2020 first-round pick, just made his major league debut on August 2 in place of Henry and acquitted himself reasonably well in a losing cause against the Giants, though his catcher (Herrera) had a rough time on the rookie’s first strikeout.

Given their current injury situation, the Diamondbacks now find themselves trying to stay afloat with just two starters who have demonstrated the ability to be league average or better, plus three rookies who have combined for a 5.63 ERA and 5.31 FIP. It’s not like the cavalry is on the horizon, either. The team’s playoff odds, which stood at 76.4% through the end of June (24.9% division, 51.5% Wild Card), are down to 21% at this writing, including just a 0.7% chance of overcoming their 8.5-game deficit to win the division. Considering that they lost 110 games just two seasons ago, they’ve certainly made progress to get to this point, but it seems quite apparent given their performance over the past five-plus weeks that they’re not quite ready for prime time.

Brooklyn-based Jay Jaffe is a senior writer for FanGraphs, the author of The Cooperstown Casebook (Thomas Dunne Books, 2017) and the creator of the JAWS (Jaffe WAR Score) metric for Hall of Fame analysis. He founded the Futility Infielder website (2001), was a columnist for Baseball Prospectus (2005-2012) and a contributing writer for Sports Illustrated (2012-2018). He has been a recurring guest on MLB Network and a member of the BBWAA since 2011, and a Hall of Fame voter since 2021. Follow him on Twitter @jay_jaffe... and BlueSky

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CC AFCmember
8 months ago

It didn’t occur to me till reading the headline, but I have seen research that human cognitive performance declines in very hot conditions and Phoenix has been as hot as it gets in July. By my quick look, it seems that they were 4-8 in home games in July. I certainly don’t think it’s the only issue, and it might impact the opposing team just as much. I wonder if the D-Backs training staff is making any effort to come up with strategies to mitigate the effects of their environment roasting their players to death – and not just like hydrating on game day, but dealing with the overall impact of living in that environment.

8 months ago
Reply to  CC AFC

Been wondering the same, and it makes me remember how once upon a time, there was lots of talk about how the fatigue of playing day baseball at Wrigley must have something to do with the Cubs’ annual “June swoon.”

But back in 2023, no amount of AC overcomes the fatigue that starts setting in when the lows don’t drop into at least the mid-70s at night, for week after week.

Then again, the Texas Rangers have been under the same heat dome, and they went 8-4 in home games in July…

Last edited 8 months ago by Transmission
8 months ago
Reply to  Transmission

it’s been lovely here in Michigan yet the Tigers still suck. So it’s probably mostly the talent level isn’t equal to Dodgers Giants and Padres yet.

Jason Bmember
8 months ago
Reply to  LMOTFOTE

What! Economist Paul Krugman, who I trust in all things, assured me that the Tigers were about to reel off five WS titles in the next seven years.

8 months ago
Reply to  CC AFC

D-backs are 4-8 in away games in July, as well.
No doubt extreme weather affects performance, but you would expect the visiting team (coming from Seattle for example) to suffer more, not less.

8 months ago
Reply to  tung_twista

The only way the argument that extreme heat is blowing up the D-Backs is if you look at it cumulatively–that somehow, living in that extreme heat degrades your abilities over time, and that you wouldn’t expect to see it over the span of a week.

The alternative hypothesis–which is the one you are proposing–is that the home team will acclimate to it and it will affect them less. Which is what I would have expected too, but I suppose it wouldn’t hurt to entertain the idea that our understanding of the effect of extreme heat on the body is wrong.

8 months ago
Reply to  sadtrombone

You do acclimate a bit, but it’s a slow and subtle process and when you start getting to 105+ and it simply does not matter. I do agree (based on nothing concrete) that the effects of the heat are more likely to be found in the accumulated stress on the body than the specifics of any particular moment in time.

Also, I’m pretty sure I’ve grown dumber living in Arizona, but that has little to do with the weather.

CC AFCmember
8 months ago
Reply to  tung_twista

I certainly don’t mean to say they’re 4-8 because it’s hot. I have no idea if it’s having an impact, but I think it’s something for teams to think about helping their players through.

I also don’t think we can expect visiting teams to be impacted more. I could equally say the D-Backs could be impacted more because of the cumulative effects of being in the heat for a whole home stand. I dont think we know one way or the other.

Smiling Politelymember
8 months ago
Reply to  CC AFC

I enjoy being a remote employee in a warm climate, but I don’t need a controlled study to tell you that I avoid working if possible during the afternoon in the summer. It’s hot and no one’s at their best.

I would think the combination of more travel/airports (thanks to the “balanced” schedule), and warming baseline temps would be an increasing burden on players, especially those in Phoenix, where walking on the tarmac to/from the plane during daylight hours might constitute a threat to health and safety.

And as a fan, you’d have to pay me to go to Dodger Stadium for a 1:10pm weekend start time. It’s just too hot now to be in the sun for that long, esp with a family, etc.