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Revisiting the MLB debut of Luke Weaver

In which I take my turn in writing about Luke Weaver's MLB debut...

Jonathan Daniel/Getty Images

After a disastrous 13-2 loss the day prior, the St. Louis Cardinals turned to 22-year-old Luke Weaver for his MLB debut on Saturday against the streaking Chicago Cubs. Should Weaver have struggled, it would not have been fair to place the blame on him considering the opponent, the location, and the fact that he made only one start at Triple-A Memphis prior to his big-league promotion -- a scenario sped up by Michael Wacha’s indefinite return to the disabled list. A ballooned pitch count in the second inning kept Weaver from making it beyond the fourth, but all things considered, he kept his club in the ballgame at a time they needed it most. Sure, the red baron already provided his thoughts on Weaver's debut, but just as he surmised in his post's second paragraph, I have chosen to write about Weaver as well (mainly because I see myself as a man of the people).

Final Line

4.0 4 2 3 3

A decent, but not great MLB debut for Weaver, to be sure. Piggybacking the start with the flame-throwing Alex Reyes was quite fun, and watching the game on the enemy's turf made the eventual outcome (a comeback victory for El Birdos) so much sweeter. Unfortunately, since SaberSeminar took place in Boston this weekend, PitchF/x guru Harry Pavlidis has not yet classified Weaver's debut on, so all we currently have is the raw pitching data coded by the MLB Advanced Media Gameday algorithm (which seems to have lost the at bat in which Addison Russell hit his two-run homer).

Sometimes there are few discrepancies found in Gameday's pitch-tagging algorithm, but unfortunately this is not the case with Weaver, as his cutter is a tough pitch for the system to classify. Thus, I'll provide Gameday's classifications in a table below, but I'll do a more in-depth job at explaining what we saw immediately afterwards (with GIFs, of course). And remember, regarding horizontal movement in right-handed pitchers, a negative value means arm-side movement, whereas a positive value means glove-side movement.

Pitch Type Count Velocity (Max.) Horizontal Break Whiffs
Twoseamer 1 92.5 MPH -6.77 inches 0
Fourseamer 45 94.0 (97.9 MPH) -5.04 inches 4
Changeup 14 84.8 (86.1 MPH) -6.75 inches 3
Curveball 10 81.0 (83.1 MPH) 2.81 inches 0
Cutter 3 90.6 (91.6 MPH) -0.04 inches 0

Weaver does not throw a two-seamer, not yet at least (when discussing Cardinals pitchers, you can never truly rule out the introduction and subsequent development of a twoseamer/sinker, even with Dave Duncan now out of the organization), so you can immediately chalk that row up as a fourseamer with more run (tailing action) than normal. As advertised, Weaver was a "fourseamer first, changeup second" pitcher in his MLB debut -- not dissimilar to the starting pitcher he replaced in the rotation.

While he certainly didn't throw Alex Reyes fast, he, too, didn't throw at a velocity where he was forced to live on, or just off, the corners of the plate in order to be successful. What I am getting at, and this is not at all meant to be a dig on either pitcher, but pitchers like Tim Cooney and Marco Gonzales must paint corners with their fastballs in order to be consistently successful at the MLB level, whereas Weaver's heater has enough giddy-up to induce swings and misses based on velocity alone (even if it is located poorly). That being said, Weaver was really close to hitting a whole lot of corners, so with more MLB experience and less debut jitters, we could soon see just how effective that fourseamer can be (again, something we never really saw from Wacha on a consistent basis). The ability to command a fourseamer is of supreme importance for a pitcher looking for consistent success with his changeup.

Not much can be said about the curveball just yet as it is definitely Weaver's least-developed pitch. Given his ability to command the fourseamer, Weaver's repertoire, centered on the fourseamer and changeup, and the emergence of a cutter, should lead to success at the Major League level. However, if he ever wants to take his performance up a notch, an adequate curveball is the logical next step, as he doesn't really have a pitch that dives down and away to right-handed hitters. He could talk to Adam Wainwright about his Uncle Charlie, but I think Carlos Martinez's slider better suits his style.

~92 MPH cutter to Dexter Fowler

MLBAM classifies this strikeout pitch as a fourseamer, but as the red baron already discussed yesterday and as is confirmed by its horizontal movement, this pitch is most definitely a cutter. For a pitcher with a fourseamer that averages ~94 MPH, 91-92 MPH is rather hard for a cutter, but considering the work Weaver still must put in with his breaking ball, the cutter is going to be a very important pitch for him in the present. Plus, I'd expect him to dial its velocity up and down given the situation, experiencing more horizontal break on the pitch thrown slower.

~86 MPH changeup to Kris Bryant

I have long believed that if a right-handed pitcher can successfully throw a changeup to a right-handed hitter (especially a dangerous one), it is probably, at the very least, an above-average pitch. Sure, baseball, in general, seems to be changing its approach to the changeup (it used to be a pitch almost used by RHPs almost exclusively versus LHHs), but the transition is not league-wide just yet.

Thus, it is extremely impressive to see a pitcher with only one start above Double-A throw a 2-2 changeup down-and-in to a powerful low-ball hitter in Bryant. Of course, it helps that Weaver was able to sequence a 97.9 MPH up-and-away fourseamer on the pitch immediately prior, but the release, ball flight, and location of the changeup was delightful. Overall, three whiffs on nine total swings is an impressive debut for Weaver's changeup, and as he fine-tunes his fourseamer location, I expect this whiff rate to hold steady, if not increase.

~94 MPH fourseamer to Kyle Hendricks

Hendricks, while a quality starting pitcher, is not a good hitter. In fact, he has struck out in roughly half (47.9%) of his plate appearances this season. However, regardless of who was standing in the box at the time, this riding fourseamer was in a nearly perfect location. While it technically could have been a touch higher and still fall in the strike zone, given this weekend's umpiring crew, I'm not certain a pitcher higher in the zone would have been called a strike had Hendricks chosen not to swing the bat. Thus, throwing a pitch in a location tempting enough to get Hendricks to swing was definitely the way to go, and even if a more capable hitter was at the plate, making solid contact would not have been easy.

Bottom Line

While Weaver's repertoire isn't as exciting as Reyes', I would not at all begin to discredit it. It already provides for a solid floor, and should he be able to add to it (via a more effective curveball), it could potentially blast his performance through its currently-projected ceiling. The progression should be fun to watch.

As always, credit to for the GIFs used in this post. If you have not yet checked out their website, I strongly suggest you do so, and you can also follow them on Twitter: @ThePitcherList.