Luke Weaver and Michael Wacha are poised to engage in a rotation battle that will benefit all the Cardinals.

Michael Wacha

Although Michael Wacha’s health has been a question for some time, his spring training performance has been promising, and he has expressed confidence in his new weightlifting routine. His spring training numbers in the past gave a pretty good indication of the year he would have in the regular season, so if he can stay healthy, expect to see good things from Wacha. Most likely, the choice between Weaver and Wacha defaults to Wacha, so the rotation battle will likely depend entirely on Weaver’s performance and development.

Luke Weaver

Luke Weaver has had very limited innings in spring training and the regular season, so any stats we have on the young right hander for the Cardinals should be taken with a grain of salt. This year he had to be pulled from a game for back spasms, and last year his minor-league season was delayed due to a wrist fracture. This is not enough to establish a pattern forming, but Luke Weaver is a slim 6’2” weighing in at only 170 lbs.

In college, a pitcher with that stature can usually be very reliable because his body is still developing and his muscles still have a measure of elasticity deteriorates with age. Weaver has reached the age where the wear and tear of throwing hundreds of pitches will start to catch up with him. To be healthy over the course of an MLB season, Weaver must gain mass and lots of it.

At Risk Mechanics

Beyond pure durability, Weaver’s mechanics give me some reason for concern. I will not delve into specific details, but if you look up Luke Weaver’s MLB page ( there is a textbook demonstration of the classic inverted W. This movement puts him at risk for a UCL injury, but only if it disrupts his timing. Looking at his pitching mechanics, it looks like his timing is usually close, so I don’t see it becoming an issue.

Unfortunately, we haven’t seen how he will pitch 150 to 200 innings into a season and how that will affect his mechanics, and we can only know once it happens. If you are interested in one of the most common factors in elbow and shoulder injuries, Chris O’Leary has excellent analysis of the inverted W (

Wacha may also have some holes in his mechanics that have contributed to his lack of durability, but I expect his new weightlifting regimen will have a greater effect than raw mechanics.


I think Wacha comes out on top, but until we see more of Luke Weaver there is no way to say for sure. Wacha has the tools to perform right now, but Weaver still has time to develop. I would love to see what Weaver could do in a long relief role, to allow him to further develop his arsenal which doesn’t seem to have the depth to start in the MLB, based on his high Whip and almost 6 ERA against major league batters.

The bottom line is that Wacha is a proven pitcher when he is healthy, and Weaver remains an unknown quantity with great potential to grow. If Wacha can recapture the success of his 2015 season, and rebuild the quality his off-speed offerings he will have a lot of success.

For the Future

That said, these two pitchers are very similar. Both pitchers mix pitches well, throwing fastballs, curveballs, change-ups, and cutters with eerily similar frequencies. Both pitchers’ success depends on the quality of their change-ups, but I believe Luke Weaver may have the slight edge when comparing the two. If Weaver develops his cutter, he has a very real chance of leap-frogging Wacha. Neither pitcher relies heavily on their curve, but Weaver could benefit from a true “out” pitch.

If he can either add some horizontal movement to his curve or working on better later vertical movement, he will add an incredible amount of depth to his tool kit that will solidify his identity as a bona fide MLB starter. For Michael Wacha, the devil is in the details. He has a lot of small things to improve on from last year that, when combined, will be transformative.

If he can apply the knowledge he gained from 2016 and remain consistent and healthy, he will be the kind of pitcher to win 15 plus games for the Cardinals or even more. I don’t think the year has come quite yet for Luke Weaver, but if he can gain weight and improve his arsenal I can see him playing an important role in the not-so-distant future.

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