Weekend Recap: Yelich and Knebel

The Brewers are in the Wild Card pole position as they enter the final week of the regular season. They went 4-2 against the lower tier of the National League Central, allowing the Reds and Pirates to score fewer than two runs a game. While it appears the division title is out of reach, the team’s playoff odds are above 99 percent so this week’s games against the Cardinals and Tigers are more about ensuring that the Wild Card game is played in Miller Park. Going into Sunday’s games, Baseball Prospectus projected the Brewers and Cardinals for identical 4-3 records which would mean the Brewers host the Cardinals for the right to play the Cubs in the Division Series.

Only a few short weeks ago, there was a legitimate question of over who was the MVP of the Brewers, as both Christian Yelich and Lorenzo Cain had strong cases. An unfortunately timed injury to Cain slowed his pace, while Yelich has only increased his production throughout the season. Since the All-Star break, Yelich is slashing .352 batting average /.417 on-base percentage /.709 slugging percentage, and he is now third amongst National League position players in Batting Wins Above Replacement Player (BWARP). Yelich has made a few changes to his approach which made this breakout possible.

Comparing pre- and post-All-Star break performance, Yelich is facing the same basic arsenal and attack plan from pitchers. As noted when I looked at his performance immediately after the All-Star break, pitchers want to attack Yelich low and away. That plan hasn’t changed over the past few months. The only notable difference in attack has been a slight uptick in fastballs. This season Yelich has seen his highest percentage of fastballs since 2015. In the first half, he saw 58.6 percent fastballs, which was up a tick from 2017, but in line with 2016 and well below the approach his first few years in MLB. However, since mid-July pitchers have thrown fastballs almost 62 percent of their pitches. Yelich hasn’t seen such a high proportion of fastballs in several years. In fact, he’s seeing 69.2 percent fastballs in September, as pitchers have almost given up on throwing him breaking balls. If that rate holds, it’d be the most fastballs he’s seen in a month of games since August 2015.

Yelich’s whiff numbers look virtually identical before and after the break. Looking at his zone profiles, he is whiffing less frequently, both above and below the strike zone when compared with earlier in the season, although he appears to only be swinging less on high pitches. One area where he appears to be locked in is breaking pitches. Yelich had been swinging at around 40 percent of breaking balls he faced, which is slightly higher than his career numbers, but not dramatically out of line. Yelich has swung at 56 percent of those pitches recently, which is completely out of character with his career.

However, Yelich is completely locked in on breaking balls at the moment. He’s killing every breaking pitch that is a strike. Those numbers are compounded by his slugging against all other pitches. Since the All-Star break, you cannot throw Christian Yelich a strike. Pitchers are aiming low, but when they miss, he smashes the ball. They are loath to pitch up in the zone, because he’ll hit mistakes there as well and whiffs at even fewer of those pitches.

The only weakness in Yelich’s game recently has been when pitchers throw sinkers. In his career he slugs .491 against the pitch, his second best number. He bested that number in the first half, but the pitch has caused some trouble in the second half of the season. Pitchers have done a good job keeping the pitch in tougher to square areas. Yelich is swinging and missing at sinkers, even when they’re thrown in his hot zones. When he does make contact, he’s hitting a lot of ground balls, which depresses his batting average against and slugging percentage.

Based on these numbers, if a team wants to get Yelich out, all it needs a sinker specialist who can place the ball low and away and not leave one over the plate. This is an exploitable weakness, and definitely something to watch when scouting potential playoff opponents. However, if a pitcher misses his spot, Yelich will hit it. If a pitcher throws anything other than a sinker, Yelich will hit it as well. If he continues his torrid pace through the next week, there is a real chance that he becomes the fourth Most Valuable Player as a Brewer.

Corey Knebel had a rough start to the season. Injuries and ineffective performance actually led to a demotion in late August to try and sort the righty out. Since he returned to Milwaukee, Knebel has thrown 10.3 innings and allowed two hits and two walks while striking out eighteen batters.

Knebel is throwing fewer fastballs in September after elevating his fastball rate earlier in the season. In his successful 2017, he threw approximately 72 percent fastballs, with the rest of his pitches curveballs. He was over 73 percent fastballs before September but is at approximately 67 percent in September, which is actually his lowest fastball usage rate over the last two seasons. The percentage differences here are all fairly small, but when a pitcher only has two pitches, and one of those pitches is hittable, then any predictability can be perilous.

Earlier in the season, Knebel’s velocity was done. In 2017, he averaged nearly 98 mph on his fastball and his velocity increased every month of the season. His April fastball velocity was around .5 mph slower this season, but unlike 2017, it has stayed relatively flat throughout the year. It also has less vertical and horizontal movement when compared with 2017 and has lost a little motion as the season has progressed.

It looks like Knebel made some mechanical changes while in the minors to try and shore up his arsenal. His vertical release point started close to this low point from 2017 and dropped through August to a new low. He has raised it in September, though he still does release the ball, specifically his fastball, at a lower point than in 2017. Knebel also appears to have moved closer to the third base side of the rubber, his furthest position in two years.

All of these tweaks have led to great results from both of this pitches. Since his return, both hits have come against his fastball, but batters haven[t had much chance against either of his pitches. The twenty seven percent whiff rate against his fastball is his best month. After laying off his fastball more early in the season, he’s inducing more swings in September.

Even though it looks like we’re seeing the 2017 Corey Knebel in September, Craig Counsell has not reinserted him into the closer role. Only 2.7 of his innings have come in the 8^th inning or later. His aLI (Average Leverage Index), a statistic that considers the game situation in which a pitcher is working, is .79 since September 1; anything below 1.0 is considered low pressure. For reference purposes, his aLI in 2017 was 2.11 and it was 1.69 before his demotion. Considering the strength of the bullpen, Knebel isn’t needed to anchor the late innings. Notwithstanding his struggles, Knebel’s 2.90 DRA is still fifth on the team. A month ago, it was questionable whether Knebel would make the postseason roster, but his recent performance shows that he can still contribute, even if in a less important role in the bullpen.

Milwaukee begins a huge three game series tonight in St. Louis. The team can clinch a playoff berth, as well as place themselves in a strong position to host the Wild Card game. The teams are 8-8 against each other in 2018, with all but three of those games occurring in the first half of the season. The Cardinals are coming in hot. They won five of their six games last week against the Braves and Giants. They’ve outplayed their expected record by 5.2 games, which is 1^st in the National League and 3^rd in MLB.