By Tyler Brandt, from Cardsblog.com
August was one incredible month for Luke Weaver. In 21 innings, Weaver posted a minuscule 1.71 ERA, striking out 29 batters against six walks. His ERA indicators were also impressive, as his FIP was just 2.63 for the month. While Weaver's run prevention did not carry over into other months, he still had a very strong season. His FIP for the season was a tidy 3.17, and his expected FIP was below 3.
Weaver was certainly in the Cardinals future plans before the season; he was one of their top pitching prospects. However, he was often overshadowed in their system. Alex Reyes obviously demanded the spotlight, and Jack Flaherty was often considered a better prospect. Nevertheless, it was Weaver who made the big-league impact last season. While he was already really good last season, I think Weaver's ceiling is a little better. Here are a few areas where Weaver has a decent chance of improving.
Weaver did a really good job of improving his ground ball rate last season. In 2016, he looked like an extreme fly ball pitcher. During his AAA stint last year, he got back up to 44 percent ground balls. While in the majors, that number climbed to 49 percent. On the other hand, Weaver did give up a high home run rate on the fly balls that he did allow. This is rarely something that keeps up over a long stretch of time.
Since FanGraphs began tracking HR/FB rate in 2003, no pitcher with at least 1000 innings pitched has a HR/FB rate above Brett Myers' 14.5 percent. Weaver's was 16.3 percent in 2017. Given that he only threw 60.1 innings, we are likely only talking about one, maybe two home runs. However, it does help explain a portion of the disparity between his ERA and FIP.
Since most baseball research in this area suggests that HR/FB rates tend to regress towards the mean the next season, it's reasonable to assume that Weaver will be league average in this department next year. That improvement would take off about .4 runs from his ERA. Again, that is an improvement that can be reasonably expected without Weaver even doing anything.
Similar to what I just wrote with HR/FB rate, I doubt Weaver's batting average on balls in play against will be as high as it was this year. He gave up a .335 average on balls in play last season, and that is pretty much what Ichiro Suzuki has hit on balls in play for his career (.336). Weaver is a very good pitcher and does not turn every hitter he faces into a future Hall of Famer. His exit velocity numbers against were very strong, and he should have given up a BABIP under .300.
Weaver was able to survive the extra base runners because of his stellar strikeout numbers. He fanned 28.6 percent of batters faced, so he stranded many runners on base. However, the point isn't that he did alright even with the high BABIP, but that his run prevention should have been better. A league average BABIP would have meant that an extra two percent of the batters he faced would have been outs. Put another way, that's the difference between a .260 and a .280 batting average against.
The point of all of this is to say that Weaver was probably better than his run prevention suggested. Sure, the Cardinals infield defense has some weak spots, so it's possible that we should have expected that. But run prevention fluctuates much more than peripherals do. It's much more likely that what happened last year was just one of those fluctuations. Regression to the mean should help Weaver here again, without him having to change anything.
What are his projections?
The two most common public projection systems are ZiPS and Steamer. They both have him doing roughly what he did last year from a run prevention standpoint. They both have him at a hair under 3.80 ERA. This is understandable, even with what I noted above. While I do think Weaver will be aided by regression to the mean in the above categories, his minor league track record doesn't suggest that he will be able to pitch in line with his 3.17 FIP or 2.93 xFIP.
In his 96.2 career major league innings, Weaver has fanned 27.9 percent of batters faced. In terms of K/9, that puts him at 10.9, which is an incredible number. However, he didn't do that in the minor leagues. Weaver was more of a control guy than a strikeout guy in the minors. In 2015, he struck out 7.5 batters per nine innings in high A while pitching over 100 innings there. He did reach 10 K/9 in AA in 2016, but last year he was under 9 K/9 in AAA. By stats alone, Weaver's high strikeout rate looks to be unsustainable for him. But I am a little more optimistic that he can maintain those numbers than the projections are.
Even though he is now 24, Weaver still has some room to add velocity. He was touching 97 last year, but he is still just 170 pounds. At 6-2, Weaver can add some lower body strength and get his average fastball up in the 94-95 range and should be able to max out higher than 97. This will add some separation from his changeup, which was already a plus pitch.
Over the past year, Weaver seems to be adding some run on his changeup. When he first came into the league, his changeup had a small drop, but not much. He just did a great job of making it look like his fastball. Now, there is some noticeable drop and movement towards right-handed batters. It looks more like a circle change now than it did when he first entered the league. That extra movement should help get more swings and misses on his best secondary offering.
Weaver's third pitch, his curveball, is still coming along. He doesn't have a consistent shape on it yet, and he is least accurate with this offering, but he is making improvements here. At its best, Weaver's curve comes pretty close to 12-6 with a sharp drop, although it often comes out as 1-7. He started throwing it more often last year and the results were encouraging.
He got a whiff on roughly 20 percent of swings against his curve, which is on the low end for a breaking ball, but not bad for someone who didn't really have a usable breaking ball three years ago. The potential for this pitch is greater, and another offseason working on it should help a lot.
If Weaver has a good offseason and comes to camp with the improved arsenal that he has the potential to reach, then he should be able to beat everyone's expectations once again. Even without a much-improved arsenal, there are some areas where regression to the mean will help. Luke Weaver has already established himself as a quality major league starter. The question is whether or not he can make the leap to the point where he is a reliable number two pitcher behind Carlos Martinez.