Since joining the starting rotation in 2017, Luke Weaver has been lights out. What if the Cardinals started the year with him in the rotation?

Coming into the year, I was bullish on Luke Weaver. Perhaps a little too bullish. I thought he was going to make the rotation for Opening Day and become a Rookie of the Year candidate. Nevertheless, Michael Wacha won the fifth starter spot in the Spring, and we didn’t hear from Weaver for awhile.

The Cardinals kept the then 23 year-old in the minors, where he carved up AAA batters for 77.2 innings. Jack Stephens detailed his impressive numbers back in June, and he earned himself a trip to the majors shortly thereafter. However, Weaver was never really given a chance. He went through two scoreless outings before heading back to the minors.

The Cardinals gave Weaver a shot in the rotation when he returned to the major leagues on July 27. He was sent down again two starts later, but returned just 14 days after that. Injuries and trades necessitated that Weaver stay in the rotation for now, but he has earned every start so far.

After giving up four runs in that July 27 start, Weaver has allowed just six runs in four starts totaling 26 innings. He struck out no less than eight batters in any of those four starts, and won all four of them.

Weaver has been brilliant since his return from the minor leagues, and his performance begs the question: what if he never was in the minor leagues?

An Upgrade Over Wainwright

I doubt that Adam Wainwright would have been the man to leave the rotation had Weaver made the Opening Day roster, but he certainly has been the worst starter. Batters teed off against him this year, making Weaver an obvious upgrade.

Including last year’s numbers, Weaver has now thrown 72 major league innings. His career strikeout rate of 31 percent would rank fourth in the majors in 2017 among qualified starters. The four pitchers who are doing better than 31 percent are Chris Sale, Max Scherzer, Corey Kluber, and Clayton Kershaw. In other words, a group that will add two more Cy Youngs this year.

Weaver’s minor league strikeout rate was never that high, so he is likely due for some regression. But 72 innings is more than enough to draw conclusions about strikeout rates. This is not a situation where we say that he can’t continue to do this well. He probably won’t, but his major league success suggests that he might outperform his minor league track record.

Control has never been an issue for Weaver, as he is once again walking less than three batters per nine innings. He also increased his ground ball rate this year to 44.4 percent in AAA and 51.2 percent in the majors. Fly balls might still hurt him from time to time, but his ground ball rate is back to where it was in 2015, which is a good sign.

Ultimately, Weaver could pass as an upgrade over any Cardinals starter except for Carlos Martinez. His peripherals match his low run prevention, and he has pushed his ceiling even higher with a strong season. With the Cardinals three games out of the Wild Card, you can’t help but wonder how this season could be a little different.

Call-Up Time for the Cardinals

Replacing Michael Wacha

For the purposes of this analysis, let’s assume that Weaver would have beaten out Michael Wacha for the fifth starter spot. In this case, Wacha goes to the bullpen, and the Cardinals go with Martinez, Wainwright, Mike Leake, and Lance Lynn as their other four starters.

Wacha has thrown 135 innings in 25 starts. However, Wacha tends to have shorter starts because he uses too many pitches. Weaver would likely get closer to 145 innings on 25 starts. To this point, Weaver has thrown 31 innings as a starter, and he has yielded just a 2.90 ERA in those starts. Steamer and ZiPS suggest that he will pitch to a 3.73 FIP the rest of the way, so let’s use that number (though Weaver’s upside is higher).

Using a weighted average of Weaver’s 2017 performance and projected 2017 performance, we get to a 3.55 ERA. That number would put Weaver behind only Martinez and Lynn among Cardinals starters. And Lynn hasn’t pitched nearly as well as his sub-3.00 ERA would indicate. Lynn is closer to Wainwright in performance this season than he is to Martinez, but you won’t figure that out by looking at his ERA.

Wacha’s 2017 ERA is 4.20, and that is only slightly higher than his peripherals suggest it should be. Since I am going by run prevention, the ERA difference between Wacha and Weaver’s projection is worth about 10 runs for the season to date. I included Weaver’s 31 real innings as a starter, so the difference is actually less. From just the projected difference as a starter, Weaver adds about 8 runs.

The other element of this is that Wacha moves to the bullpen. Rather than relievers like Jonathon Broxton and Miguel Socolovich, Wacha would be a reliable reliever. Wacha’s ERA his first time through the batting order is just 1.55 this season. That number doesn’t tell the whole story, as the second time through his ERA his over 6.00. Nevertheless, Wacha has shown the ability to beat batters the first time he sees them. For his career, he has given up an ERA of just 2.53 the first time through the order.

Add in that two runs per nine innings adjustment to 45-50 bullpen innings, and the projection creeps up towards twenty runs. Just having Weaver for the full season might not have been enough to push the Cardinals into the playoffs, but it would have put them a lot closer. As he shuts down opponents, it’s easy to wonder what might have been.

The Cardinals have a lot of young talent coming to the majors right now. It will be difficult for the Cardinals to make a run at the postseason, but they will be doing it with the right group. The Cardinals will be starting this young core next season. There is no last hurrah for the previous generation of Cardinals. The new kids are on the roster, and the team will live or die with them both this year and next. For now, they just hope that Luke Weaver continues his dominance.

Photo Credit: Sergio Estrada – USA TODAY Sports