The Diamondbacks Are the Majors’ Most Improved Team

© Rick Scuteri-USA TODAY Sports

Last year’s National League West race was a doozy, with the 107-win Giants outpacing the 106-win Dodgers, but this year’s race is shaping up to be an interesting one for a different reason. Through Sunday, all five teams owned winning percentages of .500 or better, though Monday’s loss by the Rockies (17-18), part of a 1-7 skid, upset that arrangement. Even so, it’s an impressively strong division headed by the Dodgers (22-12), with the Padres (22-13) and Giants (21-14) close behind, and the Diamondbacks (18-18) and Rockies playing quite respectably, and much improved over last season.

The biggest surprise of the bunch is the Diamondbacks, who just last year tied the Orioles for the majors’ worst record at 52-110 and finished a honkin’ 55 games out of first place. The team did not have a high-impact offseason; the only free agents the Diamondbacks signed to major league deals were starter Zach Davies and relievers Mark Melancon and Ian Kennedy, with Melancon’s two-year deal the only one stretching beyond 2022. They weren’t exactly big players in the trade market, either, with Sergio Alcántara and Jordan Luplow representing their highest-profile acquisitions. That pair has combined for 103 plate appearances and 0.1 WAR, and Alcántara was DFA’d and lost to the Padres via waivers earlier this month.

Still, thanks to some growth from the youngsters and some positive regression, as of Opening Day the Diamondbacks projected to finish with 69 wins (68.8, actually) — a total for a bad ball club but hardly a laughingstock. Their forecast put them neck-and-neck with the Pirates (68.6 wins) for the NL’s second-worst record, ahead of only the Rockies (67.5 wins), and with just a 0.7% chance of making the newly-expanded playoffs. So far the Snakes have been better than that, though it’s worth noting that they’ve been outscored by 16 runs. They’re two wins ahead of their Pythagenpat projected record, though level with their BaseRuns projected record. But even if they’re merely a .500-ish team, they’ve taken a huge step forward. By winning percentage, they’re the majors’ most improved team to date:

Most Improved by Winning Percentage, 2021-22
Team 2021 Win% 2022 Win% Dif
Diamondbacks .321 .500 .179
Yankees .568 .743 .175
Mets .475 .639 .164
Angels .475 .632 .157
Padres .488 .629 .141
Twins .451 .583 .132
Rangers .370 .441 .071
Orioles .321 .389 .068
Brewers .586 .639 .053
Astros .586 .639 .053
Pirates .377 .429 .052
Marlins .414 .457 .043
Rockies .460 .486 .026
Cardinals .556 .559 .003
Dodgers .654 .647 -.007
Indians .494 .485 -.009
Phillies .506 .486 -.020
Cubs .438 .412 -.026
Rays .617 .583 -.034
Blue Jays .562 .528 -.034
Giants .660 .600 -.060
White Sox .574 .500 -.074
Nationals .401 .324 -.077
Royals .457 .364 -.093
Braves .547 .444 -.103
Mariners .556 .444 -.112
Tigers .475 .361 -.114
Athletics .531 .395 -.136
Red Sox .568 .400 -.168
Reds .512 .257 -.255

The Diamondbacks are particularly improved when it comes to run prevention. Last year’s club allowed an NL-high 5.51 runs per game, one-third of a run more than the next-worst team, the Cubs. Through Monday, they’ve trimmed that to an even four runs per game, the league’s sixth-lowest mark. A significant share of the credit goes to pitching coach Brent Strom, who parted ways with the Astros last November after an eight-season run (2014-21) that included six trips to the playoffs, three pennants, a championship, and a pair of Cy Young award winners (Dallas Keuchel and Justin Verlander). Stars such as Verlander and Gerrit Cole, journeymen such as Charlie Morton and Collin McHugh, and youngsters like Lance McCullers Jr., José Urquidy, and Framber Valdez flourished on Strom’s watch thanks in part to his ability to blend analytics with more traditional coaching methods. Initially intending to retire at age 73, Strom was contacted by Diamondbacks manager Torey Lovullo just two days after the Astros lost the World Series to the Braves, and was out of work for less than two weeks before the Diamondbacks officially hired him.

As Sports Illustrated’s Tom Verducci detailed in a recent profile, without the ability to communicate with players during the lockout, Strom spent the winter performing an analytical study of the Diamondbacks’ pitching. He’s put his homework into action by steering his staff to throw more secondary pitches than fastballs, and to elevate more of those fastballs when they do throw them. Here’s a look at the pitch distribution, and at batters’ performances against the various pitch classifications (these stats are through Sunday):

Diamondbacks Pitch Comparison, 2021-22
Type Year % AVG xBA SLG xSLG wOBA xwOBA
Fastballs (all) 2021 61.4% .294 .278 .510 .485 .376 .366
Fastballs (all) 2022 59.3% .247 .273 .394 .485 .323 .359
4-seam 2021 36.7% .284 .270 .526 .509 .385 .378
4-seam 2022 29.3% .234 .255 .380 .451 .321 .347
Breaking 2021 23.6% .213 .206 .394 .352 .282 .268
Breaking 2022 23.5% .247 .246 .361 .391 .296 .300
Offspeed 2021 14.7% .248 .252 .416 .402 .305 .307
Offspeed 2022 17.2% .179 .217 .213 .318 .198 .249
SOURCE: Baseball Savant

The Diamondbacks’ advances haven’t been uniform. Their overall share of fastballs has only dropped by about two percentage points; on those pitches, their wOBAs allowed have dropped by 53 points, mainly as a result of the huge drop in actual slugging relative to expected slugging — a phenomenon we’ve seen all around the majors, with an average 60-point shortfall. The team is throwing far fewer four-seamers, and both their actual and expected numbers on contact have improved markedly. The Diamondbacks have given back some of those gains when it comes to breaking balls, but their offspeed pitches, which they’re throwing a bit more often, have become unhittable, with a drop of 107 points in wOBA and 58 points in xwOBA. That .249 xwOBA on offspeed pitches is the majors’ seventh-lowest, whereas last year’s .307 was its eighth-highest.

As for the elevated fastballs, Strom focused on what he calls “top-shelf heaters,” at least three feet and three inches off the ground — basically, the top few inches of the strike zone rather than simply the upper third. Here’s a year-to-year comparison:

Diamondbacks High Fastballs Comparison, 2021-22
Split Year % AVG xBA SLG xSLG wOBA xwOBA
ARI 39″+ 2021 10.0 .173 .177 .329 .353 .356 .365
ARI 39″+ 2022 11.9 .155 .193 .262 .372 .325 .364
MLB 39″+ 2021 12.6 .158 .150 .275 .265 .319 .315
MLB 39″+ 2022 12.8 .160 .166 .265 .313 .319 .331
ARI Zones 1-3+ 2021 22.6 .233 .228 .420 .408 .346 .343
ARI Zones 1-3+ 2022 25.4 .208 .243 .328 .415 .303 .340
MLB Zones 1-3+ 2021 24.5 .213 .207 .369 .358 .318 .315
MLB Zones 1-3+ 2022 24.7 .216 .226 .359 .415 .324 .340
SOURCE: Baseball Savant
39″+ = pitches 39 inches above the plate or higher
Zones 1-3+ = Gameday Zones 1,2,3, 11, and 12

Those fastballs 39 inches and higher are particularly effective, and the Diamondbacks have shaved 67 points of slugging percentage off their results while the major league average has fallen just 10 points. Even when looking at the upper third of the strike zone and higher, the Diamondbacks have trimmed 92 points of slugging percentage off their offerings while again, the major league average has fallen by just 10 points.

Through Monday, Arizona’s starters ranked second in the league in ERA (2.59) behind only the Dodgers, second in home runs per nine (0.70) behind only the Giants, and fifth in FIP (3.54) despite ranking just 10th in both strikeout and walk rates (19.9% and 7.6%, respectively). That -0.95 ERA-FIP gap owes plenty to the rotation’s ability to generate soft contact. The unit’s .240 BABIP is 17 points lower than any other NL team, with its 87.4 mph average exit velocity, 34.2% hard-hit rate, and 6.8% barrel rate all third, the last in a virtual tie with the Phillies and Marlins.

Individually, three of the Diamondbacks’ five starters are carrying ERAs below 2.00, well ahead of their FIPs. Zac Gallen leads the way with a 1.05 ERA and 2.23 FIP, and both his 3.9% walk rate and 0.26 homers per nine would put him among the league leaders if he had enough innings to qualify (his 34.1 leaves him 1.2 short through Monday). Thanks to a reworked, more coiled delivery, the 26-year-old righty has gained a full tick on his four-seamer (to 94.4 mph) and is going upstairs with it more often. Batters have slugged just .242 against the pitch, down from .368 last year. Gallen is also using his cutter a bit more often (11.6%, up from 8.3%), and has increased its spin rate and its movement. The pitch was hit for a .343 AVG/.543 SLG last year, but so far batters have managed just a .111 AVG/.167 SLG against it.

Merrill Kelly, the staff leader in innings (42), has a 1.71 ERA and 2.46 FIP, not to mention an even lower home run rate than Gallen (0.21 per nine). His fastball has gained 0.9 mph over last year, and he’s using it less but getting better results, including a slugging percentage against that’s dropped from .598 to .394. Meanwhile, he’s significantly increased his usage of both his cutter and changeup and both of those pitches are getting better results as well; batters are hitting .196/.239 against the changeup, down from .257/.367 last year.

Madison Bumgarner, whose first two seasons with the Diamondbacks largely disappointed to the tune of a 5.07 ERA and 5.20 FIP, has a 2.29 ERA but a 4.57 FIP thus far. He’s doing it with smoke and mirrors, surviving thanks to a .222 BABIP, 43 points lower than last year, with virtually identical Statcast numbers. Strom moved him from the first base side of the rubber to the third base side, and encouraged him to rely more upon his cutter, which he’s throwing 50.2% of the time (up from 34.3%) and with more velocity (from an average of 86.0 mph to 87.8) and greater elevation; batters have gone from hitting that for a .263 AVG and .468 SLG to .205/.321. But even with that improvement, and a four-seamer whose 91.0 mph average is approaching his 2018-19 levels with the Giants, his strikeout rate is down to 14.3%, the fifth-lowest of the 101 pitchers with at least 30 innings as a starter. His 4.8% strikeout-walk differential is just over one-third of last year’s 13.9%.

To watch Bumgarner against the Dodgers on Monday night was to see him lose out to the Regression Monster. He held the team scoreless on three hits through four innings before allowing three hits, two walks, and three runs in the fifth, coughing up an early 2-0 lead. Four of the Dodgers’ eight hard-hit balls against him occurred in that frame; Dodgers facing him for a third time went 2-for-4 with a double, a walk, and an average exit velo of 99.3 mph. The 32-year-old lefty’s BABIP rose by 17 points off that outing alone.

Davies, now pitching for his fourth team in as many seasons, has posted a 3.57 ERA and 3.90 FIP. The sinkerballer’s 48.5% groundball rate is his highest since 2017, and he’s generating lots of soft contact; his 85.0 mph average exit velocity places him in the 94th percentile, while his 29.4% hard-hit rate places him in the 90th. He’s increased the usage of his changeup from 32.5% to 38.6%, and where batters hit .258/.472 against it last year, they’ve managed just .175/.246 against it this year. As for his cutter, which he uses almost exclusively against lefties, batters are just 1-for-15 against it while averaging a meager 72.6 mph exit velo.

Fifth starter Humberto Castellanos, a 24-year-old righty sinkerballer whom Strom worked with in Houston (the Diamondbacks acquired him off waivers in January 2021), began the year in the bullpen but has managed a 3.95 ERA and 4.14 FIP as a starter. He’s almost completely ditched his four-seamer (which he threw 22.3% of the time last year, down to 12.6% this year) in favor of a much-improved slider (from 6.5% to 20%), and so far batters have hit .150/.300 against it.

While happy stories abound in a rotation that can offer a competitive starter every night, the bullpen has been a shakier proposition, as the unit’s 4.89 ERA and 4.35 FIP are both 13th in the NL, and its 17.7% strikeout rate dead last. Melancon, whom the Diamondbacks signed to a two-year, $14 million deal, is 7-for-8 in save chances but has taken five losses, four of them after entering tie games, and his 8.49 ERA and 5.07 FIP are both unsightly; he has more walks (five) than strikeouts (four) in his 11.2 innings, and both are in single digits, percentage-wise. Kennedy (3.45 ERA, 4.38 FIP) has been replacement level while his strikeout and walk rates (14.1% and 12.7%, respectively) play chicken as well. Setup man Joe Mantiply and middleman Kyle Nelson have both sparkled, with ERAs and FIPs below 2.00, but middleman Noé Ramirez has not, and 40-year-old Oliver Pérez appears to have reached the end of the trail just four innings into his 20th major league season; he was released in late April.

If the bullpen has been shaky, the offense has been downright anemic. The team’s 3.56 runs per game is second-to-last in the NL, and its .203 batting average, .289 on-base percentage, and 86 wRC+ are all dead last. The foundation of the offense, such as it is, is patience (10.1%, tied for third in the league) and power (37 homers and .152 ISO, both fifth); meanwhile, the team’s .247 BABIP is the lowest mark in the league by 24 points, and its .226 xBA is the majors’ lowest mark by seven points.

Individually, Daulton Varsho and Christian Walker are the only regulars who have managed a wRC+ of at least 100. Varsho (.246.331/.458, 119 wRC+) has taken a step forward after a solid rookie season (98 wRC+, 2.2. WAR) to become the team’s top hitter while making 22 starts in center field and seven behind the plate. He’s hitting the ball harder than last year, improving his barrel rate from 7.3% to 10.6%. Walker leads the team with seven homers, and he’s barreling the ball at a 14.9% clip, more than double last year’s rate, but he’s been victimized by the deadened ball. He’s got a .278 xBA and .632 SLG but is hitting just .207/.299/.438 (109 wRC+). His 194-point gap between his expected and actual slugging percentages is the majors’ 10th highest, and his 71-point expected/actual batting average gap is 20th.

Beyond that pair, six regulars — second baseman Ketel Marte, outfielders David Peralta, Cooper Hummell, and Pavin Smith, and infielders Geraldo Perdomo and Nick Ahmed, the last of whom has been limited to 17 games by a shoulder injury and now the COVID-19 protocol — have a wRC+ in the 94-97 range. Luplow has hit a lopsided .190/.261.476 (106 wRC+) in part-time duty, but Josh Rojas and Carson Kelly have been black holes of production, with the last hitting just .105/.150/.123 (-20 wRC+) in 60 PA before landing on the injured list with an oblique strain. Alek Thomas, a 22-year-old center fielder who ranked second on the team’s prospect list and 23rd on the preseason Top 100, is off to a promising start, with a .304/.333/.565 line through eight games and 24 PA, but overall, yikes.

Altogether the Diamondbacks have played uneven ball so far, and they still project to win just 73 games, with just a 1.9% chance of making the expanded postseason. Even so, they’re miles better than last year’s unsightly debacle thanks in large part to Strom, and on any given day, capable of giving their division foes more than they bargained for.

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. Follow him on Twitter @jay_jaffe.

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1 month ago

It also helps that all their pitchers didn’t get hurt yet. But turning Castellanos into a viable starting pitcher of some kind, even one at the back end is awfully impressive. So is taking Merrill Kelly to another level.