Jon Lester’s Well-Timed Hot Streak

The Cardinals’ 10-game winning streak has given them control of the race for the second NL Wild Card spot, as they’ve built a four-game lead over the Reds, reduced their magic number to clinch a spot to eight, and threatened to cut my Team Entropy workload way down. Monday’s victory over the Brewers, their ninth win in that streak, marked the 200th career win for Jon Lester, thereby increasing the count of active hurlers who have achieved that milestone from two to three, as the 37-year-old southpaw — who was acquired from the Nationals at the July 30 deadline — joined Justin Verlander (226) and Zack Greinke (219).

Before you ask: no, I don’t think this does much for Lester’s Hall of Fame case, not with a 39.5 JAWS, which ranks 156th among starting pitchers, below the likes of Cliff Lee, Jamie Moyer, Carlos Zambrano, Brad Radke, Bartolo Colon and current teammate Adam Wainwright — and more than 20 points behind Verlander, Greinke, and Clayton Kershaw, all of whom are around the Hall of Fame standard (61.7). Two-hundred wins, five All-Star appearances, three World Series rings, and three top-five Cy Young award finishes is a nice set of credentials, but let’s not go overboard.

Anyway, Lester pitched badly with the Nationals, and he wasn’t so hot over his final two-plus seasons with the Cubs, either, as his diminished strikeout rate caught up with him. His tenure with the Cardinals — who were just 51-51 with 2.1% Playoff Odds when they traded outfielder Lane Thomas to the Nationals in exchange for him — began in similarly dismal fashion. Yet over his last six turns, he’s delivered a 2.27 ERA in 35.2 innings, allowing no more than two earned runs in any of those outings, which have come against the Tigers, Reds (twice), Brewers (twice), and Mets. Then again, a peek at Lester’s FIP during that six-start stretch (5.68) — driven by a gaudy 2.02 homers per nine — suggests that not all that much has changed for him, so the question is, what’s underlying those better results?

To backtrack a bit, the well-decorated Lester pitched to a 5.16 ERA, 5.14 FIP, and 5.85 xERA last year, the final one of his six-year, $155 million deal with the Cubs. Even without the team’s questionable decision to tear things down and head into rebuilding mode despite winning the NL Central last season, the Cubs’ declining their end of Lester’s $25 million mutual option in favor of a $10 million buyout made total sense. Lester signed a one-year, $5 million deal with the Nationals in late January, but missed time during spring training to undergo a parathyroidectomy, and then tested positive for COVID-19 amid the Nationals’ first outbreak of the season. He finally made his season debut on April 30, and over the course of 16 starts, posted a 5.02 ERA, 5.42 FIP, and 4.90 xERA in 75.1 innings. It wasn’t pretty.

Through 10 starts as a Cardinal, the bad ones (7.08 ERA and 5.27 FIP in 20.1 innings over his first four turns) and good, Lester has a 5.53 FIP and 5.09 xERA… but a 4.02 ERA, which is right around the park-adjusted league average. In other words, by every indicator but that last figure, he’s actually pitched worse as a Cardinal than as a National.

For context, here’s an updated version of the table I put together when Lester signed with Washington:

As with last time, I’ve broken up those periods into unequally-sized chunks, which for Lester’s Cubs years do correspond to the observed trend in his declining peripherals as measured by FIP-, and then for his recent changes in scenery. As you can see, his fastball velocity (measured by Statcast this time instead of Pitch Info) is declining and he’s giving up more barrels and homers than in his Cubs heyday. His strikeout and walk rates are converging like two high school hotheads playing chicken on a strip of highway; his overall 14.0% strikeout rate and 5.7% strikeout-walk differential are both the majors’ second-lowest among pitchers with at least 120 innings. His FIP- keeps increasing… but since changing teams, his BABIP has dropped 59 points.

In both his Nationals and Cardinals stints, Lester is actually doing a better job of limiting hard contact relative to his final season with the Cubs…

…which isn’t saying much, though both his barrel and hard-hit rates have improved from last year’s 38th percentile to marks in the mid-50s overall, and have shown additional improvement in his move from Washington to St. Louis. What you can see in looking more closely at his actual and expected batting average and slugging percentage is a bigger swing; where his batting average was 31 points higher than expected with the Nationals, it’s now 12 points lower with the Cardinals, and for slugging percentage, he’s gone from 62 points over expectations to three points.

One thing to note is that Lester has tweaked his pitch mix since coming over to the Cardinals, throwing more sinkers and fewer four-seam fastballs and cutters. All three pitches have gotten better results:

Those better results have been offset by worse results on the changeup and curve, but it’s still translated to some improvement in the actual numbers, if not the expected ones.

The St. Louis Post-Dispatch’s Derrick Goold recently explained Lester’s remixed repertoire:

After the last-minute deadline trade that brought him from Washington, Lester met with Maddux and other coaches to go over a “snapshot” of his pitch effectiveness and usage. The coaches suggested a shift in his mix of pitches to make the cutter — his best pitch — more effective and possibly even rely on it less. He also could use the outside part of the plate against righthanded batters more effectively. That meant trusting his changeup out there. He has started to use it to play off his fastballs in the same way Wainwright flexes his curve.

It was, effectively, a trust fall.

He had to let his stuff lean out — and they’d catch him.

Via The Athletic’s Ken Rosenthal, Lester recently explained, “It’s more or less throttling back and forth rather than the, ‘Here it comes, let it eat,’ type deal.”

Some of Lester’s in-season improvement may owe to better pitching and better luck, but a good chunk of it is probably due to having a superior defense behind him. Through Sunday — the cutoff for all of the defensive stats that follow — the Nationals rank eighth in the NL in defensive efficiency (.696, two points below league average) while the Cardinals are second (.715). In terms of Ultimate Zone Rating, the Nationals are last in the NL (-19.1) while the Cardinals are third (22.3), while by Defensive Runs Saved, the Nationals are 12th (9) and the Cardinals first (83). We don’t have monthly defensive splits, but consider the full-season numbers for the typical lineups behind Lester with both teams:

Quantitatively, the catchers and right fielders are close enough that there’s no clear advantage for either side, and that’s before I cloud the picture by including the backup backstops (the framing of Andrew Knizner, who has caught three of Lester’s starts, is atrocious, -5.9 runs in just 349.2 innings this year — and that represents his improvement over 2019-20). At every other position, where the Nationals mostly have solid defenders, the Cardinals have good to excellent ones. For a pitcher like Lester who’s not missing many bats these days, that’s huge. That 2.27 ERA hot streak owes plenty to a .184 BABIP, which is unsustainable. It also owes something to good sequencing; of the 10 homers that Lester has allowed as a Cardinal, only the first of them had a runner on base; the other nine were solo shots.

Given Lester’s shaky peripherals, it’s been at least somewhat amusing to see the praise heaped upon his acquisition and subsequent performance, but it helps to consider the baseline against which he’s being measured. Lester has pitched roughly to replacement level by both fWAR (-0.1) and bWAR (0.2), as has fellow July 30 acquisition J.A. Happ (0.2 fWAR, 0.1 bWAR via a 4.33 ERA and 4.97 FIP). In the aggregate, it’s a tossup as to whether they’ve out-pitched the guys they immediately replaced, Johan Oviedo and Jake Woodford; by fWAR (-0.1 apiece this year), the answer is no; by bWAR, the answer is a slight yes when it comes to both (-0.6 and 0.0, respectively), with the newcomers’ lower ERAs coloring the perception of bigger improvements. That’s been particularly true relative to the injured Carlos Martínez (6.23 ERA, 4.75 FIP, 0.5 fWAR, -1.3 bWAR), who’s been out since July 4 following surgery to repair a torn ligament in his right thumb.

Indeed, the mere stability and familiarity of Lester (and Happ) is a big deal on a team where Adam Wainwright is the only pitcher to make more than 21 starts, and Kwang Hyun Kim the only other one to make more than 16, while Jack Flaherty and Miles Mikolas have combined for just 21. Lester’s presence, and his getting hot at the right time, has served the Cardinals well. We’ll see how long the smoke and mirrors last.