Rookie pitchers have not "shut down" the St. Louis Cardinals in 2015

Rookie (meaning "unknown, no name") pitchers "shut down" the St. Louis Cardinals is a persisting narrative that hovers around social media in the days preceding and the day of a start by a relatively unknown rookie starting pitcher. The narrative does not stop at just rookie pitchers, though, but rather, a qualifier is added that the offense especially struggles when they face a rookie pitcher for the very first time, seemingly stressing the supreme importance of in-game experience—rather than reliance on video and/or scouting reports supplied by the hitting coach.

Since "shut down" is inherently vague, I took to Twitter to crowdsource a generally accepted definition for this term. Looking back, I should have made a Google form to receive more consistent responses, but the general consensus for "shut down" was at least six innings pitched, no more than six hits, no more than two earned runs, at least one strikeout per inning, and no more than two walks. Overall, I respect this "definition" even though I think an average of one hit per inning is slightly lenient toward the pitcher. Since narratives are propagated by the population, I felt it was only right to get a definition for a component of the narrative from the population itself.

Using Baseball-Reference's 2015 MLB debuts section as a guide, I looked up the game logs of each rookie pitcher that faced off against the Cardinals in 2015. If the pitcher had faced the Cardinals more than once, I included the first start only, in order to keep in line with the narrative.

Let's first revisit the generally accepted stat line for a pitcher "shutting down" an opposing offense:

Of the 15 rookie pitchers included in this exercise, only one met the accepted criteria, and that was Tyler Cravy in a 1-0 nailbiting Cardinals victory on June 2nd. To include Matt Wisler's seven-inning outing on July 26th, you would have to remove the hit, strikeout, and walk categories, so despite the fact that he received a "quality start," I feel safe in saying he didn't "shut down" the offense. Rather, with seven hits and three walks, it appears that the Cardinals offense suffered from unlucky sequencing in that game.

And for those wanting to include John Lamb's scoreless five-inning outing on September 10th, he walked six guys, so yeah, that doesn't qualify, either. If you adjust the narrative by also including Lamb's second start against the Cardinals on September 21st, in which he went six innings, allowing five hits and no runs (and subsequently qualifying for our definition of "shutting down" the offense), then you are obliged to include Cravy's second start against the Cardinals as well. This start was in Milwaukee on August 7th, and Cravy allowed eight hits and six earned runs over five innings.

Overall Stat Line

Resulting in:

• An average of 4.8 innings per start (Not enough to qualify for a pitcher win)
• 5.75 ERA (League average: 4.11)
• 1.72 WHIP (League average: 1.30)
• 7.13 K/9 (League average: 7.38)
• 5.88 BB/9 (League average: 2.72)

If we include Brandon Finnegan from last night (I don't know if this should count since he faced the Cardinals twice out of the bullpen prior to the start), these numbers are even worse as he allowed seven hits and six earned runs over five innings despite tallying seven strikeouts and only one walk. However, when I brought up that Finnegan was left-handed and a rookie on Twitter, I received a predictable response, leading to a modification of the narrative: Finnegan had a "good ERA" coming into the game, so, duh, he doesn't count. Plus, since he came from the Kansas City Royals in the Johnny Cueto trade, he is not really an "unknown, no name" pitcher, either.

Addendum

Narrative #2: Cardinal hitters struggle against "soft-tossing lefties"

Using the PitchF/x function on BaseballSavant.com, I sorted career batting average and slugging percentage against pitches ranging from 80 MPH to 90 MPH, thrown by a left-handed pitcher (aka a "soft-tossing lefty"), and the results are found below:

Outside of the usual suspects near the bottom of the table, plus Wong and Heyward who are susceptible to wipe-out breaking balls from lefties, there is no statistical backing to narrative #2, either. The league average slugging percentage for non-pitchers in 2015 is .412, and seven members of the Cardinals top that. In terms of batting average, 2015's league average is .259, and six Cardinals best that mark as well. I understand that getting the league average BA and SLG on 80-90 MPH pitches from lefties would provide for much better context here, but unfortunately, there is no easy way in finding this (that I'm aware of, at least), so I went with the next best option.

Narratives are fun, and purely results-based analysis is bad, but frankly, sometimes it is necessary. If you are going to perpetually promote a narrative, it is wise to see if the numbers back up what you are saying first.