Last Sunday, Jon Lester threw what might be the best start of his career to date. He didn't quite replicate his 2008 no-hitter, but with just one hit and two walks allowed, he came extremely close. Over eight innings of work, Lester struck out a career-high 15 Athletics with a dominate cutter and fastball that he was able to locate with precision. With this stellar performance, Lester now leads the league in Fielding Independent Pitching (FIP) and is currently toting a strikeout rate almost nine percent better than his career norm and walk rate that is more than three percent down from his typical rates. If he can maintain numbers like these, he will have done just about everything possible to maximize his value as he hits free agency this winter.
If the numbers stay where they are now, the team that signs Lester will be extremely tempted to toss a contract David Ross' way as well. The veteran backup backstop may be hitting a rather bleak .182/.250/.424 but a quick look at the splits between Lester pitching to Ross and pitching to A.J. Pierzynski is enough to warrant a quick call to the man's agent at least. Ross has caught five of Lester's seven starts and when he has been behind the plate, Lester has an ERA of 2.19 and an otherworldly strikeout-to-walk ratio of 8.6. In the two starts with Pierzynski, his ERA is 3.86 and his K/BB an even three. With Ross, hitters have managed just a 522 OPS, with Pierzynski catching, they have a 938 OPS.
Now, obviously, this is subject to the most extreme of small sample size warnings. Lester has pitched just two games to Pierzynski and one of those happens to be his worst start of the season. While the numbers above may not represent the true level of difference between the two catchers, a closer look at this issue supports the idea that the gap between Jon Lester pitching to Ross and Jon Lester pitching to Pierzynski is significant.
The defensive gap between Ross and Pierzynski is obvious whether you are looking at statistics or at simply watching the games. Pierzynski has rated below average in Defensive Runs Saved (DRS), Fielding Runs Saved (FSR) and Total Zone (TZ) throughout his career. His 25 percent career caught stealing rate is below average. Ross, on the other hand, is one of the more elite throwing catchers in the game, with a 38 percent caught stealing rate for his career, which has helped carry him to strong results in all the advanced fieling metrics. Visually, Ross is still behind the plate with small, smooth actions across the board, while Pierzynski is very active and has a lot of wrist movement in his catching hand.
Catchers throwing ability is often overrated, however, and obviously Pierzynski hasn't stuck at the position for 17 seasons by being completely inept behind the dish. By catchers' standards, he is a plus hitter and his defensive work is not nearly weak enough to cause pitchers to worry about throwing a certain pitch in a certain count or to allow teams to simply run at will. According Baseball Prospectus, he is actually above average at preventing passed balls and wild pitches, a key skill for any backstop. The issue for Pierzynski working with Jon Lester is related to the subtle skill of pitch framing and specifically to Ross' superior ability to frame pitches low in the zone. That skill is critical to getting the best out of Jon Lester.
According to Baseball Prospectus's current methodology of calculating pitch-framing runs, Pierzynski is slightly below-average at the skill overall, with a rate of -3 runs per 7,000 pitches for his career. That is far from a major issue for the Red Sox as long as he has solid value at the plate. Ross is an elite pitch-framer by BP's calculations, however, averaging 34.5 runs saved per 7,000 pitches over the same period. That is enough to make up for the dramatic difference in offensive ability between the two at the moment even without Ross's other defensive advantages, but since playing Ross everyday isn't a viable option, the question is not whether to start Ross over Pierzynski, but how best to employ the backup to maximize his impact. Looking at the pitch-framing data and some early results, using Ross as Lester's personal catcher appears to be a key part of the optimal deployment for this season.
To understand how Ross provides a specific advantage for Jon Lester, let's start with how Lester pitches these days. Here is his usage pattern for all his pitches care of Brooks Baseball since the start of last season:
Lester works primarily low in the zone, specifically targeting the area low and inside for right-handed hitters, the spot that he almost exclusively pitches to when throwing the cutter. This usage is working well for Lester as the zone map of his batting average against shows:
Pierzynski was actually fairly good at framing Lester’s pitches on Opening Day when the Sox lefty struck out eight over seven innings in a losing effort. However, none of the strikes Lester managed on out-of-the-zone pitches were below the zone. Instead, the former-White Sox backstop managed to help Lester on the sides of the zone, as you can see several times in the MLB recap of Lester’s performance:
In the second start in which Lester worked with Pierzynski, the catcher’s inability help him out with pitches below the zone was far more problematic. Comparing the calls the Yankees received below the zone with pitch-framing master Brian McCann catching to the ones the Red Sox staff received highlights this problem (again, care of Brooks Baseball):
McCann helped his pitchers steal nine strikes below the zone, while the Red Sox got just three calls in the same area and had one low pitch clearly in the zone called against them. Pitches that were called strikes multiple times for New York were called balls in the same area for Boston. Pierzynski may not be soley responsible for the inconsistency here, but his wrist-heavy catching action doesn't work well for framing low pitches, so some blame is warranted. It is just one game and any player can have a bad day, but when compared to what Ross is capable of doing for Lester, it seems to be reason enough to make the Ross-Lester battery permanent. Lester hardly missed the zone at all during his magnificent 15-K performance, but looking at the previous start’s strike zone map at Brooks Baseball illustrates the difference clearly:
Together, the numbers and the visual evidence are compelling, as is Ross' role in Lester's dominant October run- Ross caught four of Lester's five October starts, but they still require a grain of salt. Last season, Lester actually posted better numbers pitching to the departed Jarrod Saltalamacchia, who has been up and down as pitch-framer by BP's methodology. Even so, pitching predominantly to Ross, Jon Lester is having an excellent season so far and keeping Ross as his personal catcher seems like a no-brainer. If the reasoning above makes a compelling for keeping the Ross-Lester battery together, all of the same arguments would apply to making Ross the exclusive catcher of Boston's other lefty starter as well.
Unlike Lester, Felix Doubront is struggling this year. His numbers are fairly ugly regardless of how you split them up, but they are a little less repugnant when he throws to Ross. In 20 2/3 innings with Pierzynski, Doubront has a 5.23 ERA, a strikeout-to-walk rate of just 1.2 and 873 OPS. With Ross his ERA is 4.96, his K/BB rate is 2.4 and his OPS is 746 over 14 2/3 innings. It isn't a massive divide given the sample size, but if a change in catcher could potentially turn the average Doubront opponent from Andrew McCutchen into Chris Young, it's probably worth a shot.
Doubront employs a very similar repertoire to Lester and, like the Sox ace, he focuses his cutter to the area that sits low and in for righties. His velocity is not at the same level as Lester and his control is not going to suddenly match Lester's no matter who is behind the plate, but the key similarity between the two southpaws is their success when they locate below the zone:
Doubront's results are not as good as Lester's (obviously), but getting him more strikes below the zone would play to his strengths in a similar way. The other Sox starting pitchers have success when they work low in the zone as well, but Clay Buchholz gets his best results at the inside and outside edges of the zone where Pierzynski is better at framing and Jake Peavy has been strong working thus far exclusively with his former White Sox teammate Pierzynski. If Ross were to catch both lefties exclusively, that would give him approximately 68 games this season, which would be a reasonable number for a veteran backup. Quirks in the schedule like rain delays, doubleheaders and day games after night games probably won't allow for strict adherence to this battery plan, but matching Ross to the two lefties as much as possible would be an excellent strategy for the Red Sox to implement going forward.