A Closer Look at Luis Robert’s Post-Injury Breakout by Luke Hooper December 9, 2021 Luis Robert debuted in 2020 as our No. 7 prospect in baseball and put up up a strong rookie season with league average offensive numbers (100 wRC+), and stellar center field defense (8 Defensive Runs Saved), helping the White Sox return to the playoffs. Under the hood, though, there were some red flags. He had the worst SwStr% in baseball at 22.1%, as well as a 32.2% strikeout rate. His O-Swing rate of 43.1% was fourth worst in baseball, and even when he did make contact, he had a below-average exit velocity of only 87.9 mph. The 2021 season started off with a similar level of production until Robert suffered a torn hip flexor in early May that would end up costing him the middle three months of the season. When he returned to action in early August, he immediately looked like a different hitter, putting up a 173 wRC+ over the rest of the season and, perhaps most impressive of all, dropping his SwStr% all the way down to 14.5% — not quite league average, but nowhere near the outlier he had been prior to his injury. Check out the contrast in his career numbers before and after his injury: Robert’s Career Splits Pre-Injury Post-Injury PA 330 193 AVG .259 .350 OBP .320 .389 SLG .444 .622 wOBA .327 .424 BB% 8.2% 3.6% K% 30.6% 17.1% SwStr% 21.5% 14.5% Exit Velo 88.3 92.0 Barrel% 11.9% 13.5% As you can see, his gaudy offensive performance is now being backed up by a huge improvement in his strikeout rate, as well as much better quality of contact. As it turns out, while Robert was sidelined by his injury, he was doing more than just working on his recovery; he was also working with hitting coach Frank Menichino on some tweaks to his stance and approach. The Cuban outfielder talked about that with The Athletic’s James Fegan in late August: “I didn’t make any big changes. Maybe my front foot is a little open to the left, but just barely. The only thing I changed is my approach with two strikes. I’ve been starting earlier, but that’s honestly the biggest and only change I made in my stance.” There’s a lot to parse there, but let’s start with his legs. He did indeed return from his injury with a more open stance; look at how it just kept getting more and more open as the season progressed: I think Robert liked the result of opening up his stance so much that he just kept expanding it. Now, why did he like the result? From the side, you can start to see what that open stance is helping him accomplish with his hips: The open stance forces his leg to move toward the plate with less movement going toward his back leg. Less backward movement causes his hips to twist less. The stance allows him to keep the big leg kick as a timing mechanism, but the movement is no longer jamming up his hips, creating a quicker drive to the ball. As for the part of his quote about a two-strike adjustment, I can’t exactly say I’ve seen much, in video or in his stats, to back up a specific change there. I do, however, think that it reveals a conscious effort to make more contact, which probably bled over into his overall approach, especially if the new stance shortens his drive to the ball. His swinging-strike rate in two-strike counts after he returned (13.2%) was marginally better than outside of those counts (15%), but his overall swinging-strike rate was much better after these adjustments (21.5% down to 14.5%). This wasn’t merely a two-strike improvement in his contact; he hit the ball more often across the board. One of the biggest areas of improvement for Robert was in his ability to punish fastballs. Those were his worst pitch type and an early weakness, with a whiff rate of 16.9% and all-around below-average performance. Fastballs aren’t exactly a swing-and-miss pitch: the league-average whiff rate for all types is only 8.7%. But after that stance adjustment, Robert crushed fastballs, lowering his SwStr% to 10.8%. Performance Against Fastballs Pre-Adjustment Post-Adjustment BA .241 .404 OBP .317 .454 SLG .352 .727 wOBA .297 .495 Exit Velo 90.7 93.1 SwStr% 16.90% 10.80% SOURCE: Baseball Savant Struggling with fastballs is usually a sign that a hitter’s swing may be a bit too long. The contact improvement and overall production increase suggests that Robert is now better suited to catch up to velocity. It was a remarkable turnaround for him, one of the best fastball hitters in baseball over the final two months. Unlocking more contact is one way to improve plate discipline, but a more fundamental skill is the ability to make good decisions about what to swing at. This is where Robert has struggled throughout his young career, and even during his torrid second half, he showed little improvement in that area. Since his debut, he leads baseball in Swing% and in swinging at the first pitch; both of those increased after his return from injury. Swinging isn’t objectively bad (although our Devan Fink has some interesting thoughts on that), but it’s hard to be a really good hitter when you swing as often as Robert does. The following graph plots Swing% against wOBA for every season since 2015, minimum 250 plate appearances: Robert is an outlier in terms of being extremely productive with a swing rate that high. The problem for him is that this aggressiveness isn’t just contained within the strike zone; even after his return, he still had one of the highest O-Swing rates in baseball: Plate Discipline Pre-Adjustment Post-Adjustment Zone% 37.9% 40.5% Swing% 58.5% 61.3% Z-swing% 82.0% 88.4% O-Swing% 44.2% 42.9% SwStr% 21.3% 14.5% Robert’s O-Swing% showed minor improvement but was still too high and could hold him back if pitchers tease him out of the strike zone more than they do now. He actually saw more pitches in the zone (Zone%) as the season went on (and saw a roughly league-average Zone% last season), which seems like a mistake the league won’t make next season. What will happen when pitchers start treating him closer to the likes of Javier Báez and he starts seeing a Zone% more befitting his aggressiveness? That’s where he needs to continue to grow and adjust, and I imagine pitchers will force the issue on him next season. Robert made some notable improvements in 2021, which speaks to his ability to make more improvements in the future, and we still haven’t even seen a full season out of him yet. His elite defense and explosive bat will keep his floor astonishingly high; just look at his 4.7 career WAR in 523 plate appearance. If he can develop a bit more patience outside the strike zone, we could be looking at an MVP candidate in the coming years.