Among Twins fans, few players have been given a shorter leash despite showing flashes of solid play than Brent Rooker. While Rooker’s results in 2021 have hardly been inspiring, the underlying data says Rooker may be much better than his weak triple slash has shown so far. 

So what are his “results” so far? Regardless of the metrics you want to use, be it the traditional triple slash or others: .201/.294/.397, OPS .691, wRC+ 91, wOBA .302 or OPS+ 90, Rooker’s offensive production has been below par. In fact, for somebody who is touted as a glorified DH, way below par. Rooker would really be expected to produce an OPS above .750 to remain viable and over .800 to produce good value. Of the 15 players who qualify as “DH” with more than 300 plate appearances in MLB this year on Fangraphs, the median OPS is Josh Donaldson’s .816.
On his way to the triple slash he’s produced, Rooker has struck out 32.5% of the time while walking in just 7.6% of his plate appearances. That’s not a great ratio, but for a power hitter, 32.5% K rate isn’t unusual and it’s also in only 197 plate appearances so far this year. This is, for all intents and purposes, Rooker’s rookie season and his first taste of MLB action after showing far above average production in the high minors for years now. The question at this point is not whether Brent Rooker is too good for AAA, it’s whether or not he’s destined to be labeled a AAAA player.
I’ve seen some other posts suggesting Brent Rooker may be cooked already, but a dive into some of the advanced metrics show a very different set of numbers.

*BaseballSavant has xBA at .237 and xSLG at .449 which result in 41.24 hits and 78.13 total bases. Those aren’t real numbers so I rounded them down to 41 hits and 78 total bases. I used Rookers actual walks and hit by pitch numbers to calculate his new xOBP so I could calculate his xOPS.

So Rooker’s expected batting line numbers are far better than his actual results, but that can be true for a lot of hitters who don’t use the whole field because of the shift; however, Rooker is not the typical dead pull hitter who is helpless against the shift. Of course, Rooker does pull the ball a lot, 44% of the time in fact, but he also goes to the opposite field 26% of the time. Among qualified hitters, Rooker is actually in the top half of hitters going to the opposite field and he’s not in the top 25% in pull hitting. Fangraphs has limited data on Rooker’s plate appearances, but he gets shifted against about 59% of the time vs. say Max Kepler who gets shifted against 97% of the time (yes, 97% is the real number). Another consideration is whether or not the shift should even actually hurt a hitter. Ground ball hitters are hurt the most, then fly ball hitters, then line drive hitters. The shift is less effective against line drive hitters because the balls generally have high exit velocities and hit the ground quickly so even if defenders are “shifted,” the ball really has to be hit directly at the defender in order to have a play. Despite his excellent power, Rooker is more a line drive hitter than a pure fly ball hitter. He very rarely pops the ball up, and Fangraphs has him at 26% line drive and 38% fly ball with Baseball Savant having him at 31% line drive and 31% fly ball. With Rooker’s batted ball profile, the shift should not be highly effective against him.

Beyond Rooker being somewhat shielded from the shift, there are other things to consider when it comes to hitting. Exit velocity, launch angle, hard hit and barrel rates are extremely important when trying to figure out whether or not a hitters bad luck is actually bad luck and not a function of just a lot of weak contact. Rooker’s average exit velocity is very good at 90.9mph (top 82% in baseball). His launch angle is 12.8% this year which reflects the high line drive rate, but it’s not quite high enough to be “optimal” for a hitter with Rooker’s power. There’s a hard core, in depth article on Fangraphs if you’re interested in getting into the deep end of the pool (I’m not, haha). https://fantasy.fangraphs.com/lets-talk-about-launch-angle-generally/ Rooker would probably experience better slash lines and an increase in home runs with a launch angle closer to 20* because of his power, but he should be very close to having his optimal batting average where he is. What about hard hit rate? Fangraphs says Rooker is 35.5% hard hit rate based on Baseball Info Solutions algorithms, which is good for the top 37% of hitters with 300 plate appearances, but BaseballSavant has Rooker with a higher 47.6% hard hit rate (different definition at 95mph+) and puts him in the top 15% of hitters with 100+ batted ball events. When it comes to barrel rate, Rooker is showing up as 11.8% putting him in the top 16% of hitters for Fangraphs and BaseballSavant. Btw, think of barrel rate as absolutely crushing a ball. The baseline is a launch angle of 25-31* and an exit velocity of at least 98mph. For every 1mph of exit velocity you add, you get about 2 degrees more leniency in the launch angle. Like 100mph gets you to 24-33*. It’s that no doubter home run or absolute rocket off the bat where no amount of shift makes any difference because the ball is in the outfield before the infielders even know what happened.
Some charts to help folks who don’t follow metrics closely. This data was pulled from Fangraphs using Statcast numbers for the 252 players with at least 300 plate appearances this year prior to today. Rooker himself was not included as he only has 197.
 

Now we can discuss his plate discipline. Does Rooker have the hit tool to play at the MLB level? How do opposing pitchers view him? BaseballSavant shows pitchers have become wary of testing Rooker, throwing him fewer fastballs and more breaking balls while avoiding the strike zone as much as possible. Interestingly enough, Rooker has better results against the breaking balls than fastballs, but according to the expected data, it should be the exact opposite. Rooker against the fastball is batting just .177 with a SLG of .375, but his xBA is 80 points higher at .256 and his xSLG is .487.  Rooker’s performance against breaking balls is closer to where it should be with a .245 AVG vs. xBA of .225 and a SLG of .434 vs. an xSLG of .418. His bat is not a black hole against breaking pitches in practice or theory and his bat looks like it should be downright dangerous against fastballs and changeups. In regard to plate discipline, Fangraphs shows his O-swing% (swing percentage of pitches outside the zone) at 30.6-32.3% depending on the source, but that’s not bad at all. His PitchFX data shows Rooker swinging outside the zone at 32.3%, which would rank as better than 43.5% of MLB hitters with more than 300 plate appearances so far this year. A tick below average. His contact rate on balls outside the zone does need some work suggesting he can be completely fooled a bit too easily. His Z-swing% (swing percentage of pitches inside the zone) rates are a little lower than they should be and Rooker takes too many called strikes because he’s not aggressive enough when he gets a pitch in the zone. Again, based on players with 300+ plate appearances from PitchFX data on Fangraphs.

Lastly, something pretty interesting to me. Defense. While Rooker carries with him the expectation he’s a lost cause at the corners, BaseballSavant hints at Rooker not being a guaranteed waste in the outfield. Rooker’s sprint speed is above average. Yes. You read that right. His sprint speed on BaseballSavant shows 27.3 ft/sec, above average for an MLB player or left fielder for that matter. His defensive metrics show Rooker is above average when it comes to route running, but his reaction is terrible (feet in 0 to 1.5 seconds) with Rooker’s acceleration in sprint speed being iffy. The combination of Rooker not recognizing the ball off the bat quickly enough and his mediocre acceleration is what is hurting Rooker defensively. Some of that can be improved with work and experience, though it’s a little bit late for Rooker to take an active role in becoming a better fielder.

In summary, What does all of this mean? Well, for starters, we don’t have a ton of data on Brent Rooker. He’s only at 197 plate appearances this season and a paltry 21 from 2020. At about 200 plate appearances in a season is where the first set of luck metrics just start stabilizing and they move quite a bit to 300 plate appearances where things start to get pretty stable. Rooker shows adequate plate discipline, his batted ball profile suggests he’s having terrible luck, but he’s frequently shown off his power. Opposing pitchers have formed enough respect for Rooker that they’ve made the adjustment to try to avoid throwing him anything decent to hit and Rooker hasn’t turned into a strikeout machine in the process. Rooker is primarily a pull hitter, but he’s gone to the opposite field enough to keep defenses semi-honest on the shift. Rooker also hits the ball much harder than the average major leaguer, he barrels up the ball well enough and doesn’t make a lot of weak contact. It seems like Rooker needs to be more aggressive when he gets a strike rather than waiting for a meatball because MLB pitchers are definitely being extra careful not to give him something easy to hit and MLB pitchers do not make mistakes like MiLB pitchers do. An MLB hitter might see 1 mistake pitch per game vs seeing several in the minors. Defensively, he waits a little too long to make a jump on the ball and he could work on improving his running technique to get better off the line acceleration, but he has the speed to cover a corner outfield position. With a little opportunity for his luck to even out and some minor adjustments, Rooker may turn into a real force at the plate with adequate corner outfield defense. Despite his limitations, it’s too soon to pull the plug on Rooker as he’s definitely got the potential to be a legitimate every day starting MLB player.