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Predicting Rookie SP Success

I didn’t plan on writing an in-depth article today, but my unhealthy obsession with stats and patterns got the better of me.

While my waffles were in the toaster this morning, I clicked over to the fantasy league that we at Baseball Professor had just drafted this past weekend. Yesterday, Chris Campanelli and I were discussing a trade that would involve me getting Wade Davis. I like Davis. I like the potential he has and the offense that supports him, but I’m already rolling the dice with Brian Matusz. The questions then became “What are the chances that Davis or Matusz will break out this season?” and “If so, which of them is the better option?”

What was supposed to be a quick between-waffles query morphed into a massive search to uncover some underlying predictor that would help me – and the rest of the fantasy community it seems – decide which rookie starters are most likely to be fantasy-relevant.

I spent a long time combing through scouting reports, minor league and spring training stats, and PitchFX data – basically anything I could get my hands on – in an attempt to satisfactorily answer my questions. Before jumping too far into the numbers, I needed to decide what criteria indicate the potential for an impactful rookie season. To do this, I looked at resumes of some of our more recent rookie successes.

These aren’t the largest sample sizes, but I don’t have the time, resources, or patience to undertake such a massive task (someone page ESPN). Despite these shortcomings, this analysis gives us as good a head start as I could hope for, at least for a Thursday morning.

WARNING: The intro to this article is stat-heavy and explains how I arrived at the Breakout Predictors I selected. If you want to skip right to the results, click HERE.

Major League Success

These are all of the starters who received at least one Rookie of the Year vote since 2007 (excluding Daisuke Matsuzaka). And no, Clayton Kershaw‘s omission is not a mistake. He didn’t receive any votes, and from a fantasy perspective his rookie season just wasn’t that good.

[table id=26 /]

If you had any of these starters during their rookie seasons, you received the perks of a quality starter who performed like a seasoned veteran. Starting below, we’ll compare these players backgrounds with others who didn’t nearly have as much success.

Minor League Resume

Now that we’ve identified the players who have had rookie success, let’s look at what they did in the minors to see if we can find any predictors.

Note: Randy Wells made 184 minor league appearances but only 82 as a starter.

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Now let’s look at 10 pitchers who struggled mightily during their rookie seasons, all from 2009. Hopefully we can find some possible differences between their minor league careers and the careers of our rookie successes.

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Is it really surprising to anyone that players with successful rookie seasons typically had better minor league careers? It shouldn’t be. If there is one stat here that seems to indicate a greater potential for success than the others, it’s WHIP. Five of the ten successes had a WHIP under 1.20 as compared to just two of the failures.


The following data comes from FanGraphs. In the first five columns, the first number is how frequent the pitch was thrown and the number in parenthesis is the average velocity. In the last five columns, wFB/C is a notation that denotes pitch quality. The term “w” refers to “above league average” and “/C” refers to “per 100 pitches” (but the arrows are covering this so you can’t see it). Together, “wFB/C” means “quality of fastball as compared to league average per 100 pitches.” Get it? Good. So, does a 95 MPH fastball seem to be the only requirement or is the quality of your second and third pitches more important?

Note: FB = Fastball, SL = Slider, CT = Cutter, CB = Curveball, CU = Change-up.

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The numbers above may seems random and confusing at first, so let’s decide what’s important. First, eight of the 10 successes had fastballs that were at least slightly above average (indicated by a positive “w/C” value). Considering that fastballs are thrown most frequently, it makes sense that the quality of this pitch is of great importance.

Second, notice how seven of the 10 successes had two above-average pitches that they threw at least 10 percent of the time. The only exceptions to this were Anderson, Galarraga, and Porcello. Of these guys, Anderson and Galarraga had outstanding sliders to make up for their just below-average fastballs, and Porcello had the best fastball of the bunch, threw it with the greatest frequency, and excelled at pitching to contact. Let’s see if the failures can replicate this.

[table id=30 /]

Does it really come as any surprise that every single one of the failures had below-average fastballs during their rookie seasons? More telling, only Paulino, Gonzalez, and Huff had secondary pitches thrown at least 10% of the time with a “w/C” value greater than 1.0, and in those three pitchers’ cases, the rest of their repertoires were woeful.

Also note how the average velocity of the failures was actually greater than that of the successes. This would seem to indicate that the quality of the pitch is much more important than the velocity behind it. While this shouldn’t be a shocker to anyone, it reminds us not to get caught up in the hype of a player with an electric fastball (Holland and even Chris Tillman).

Our Findings

Based on the data above, I feel comfortable making the following generalizations:

  • Minor league stats are not the best predictor, however minor league WHIP does seem to have an above-average level of importance. As a baseline, a WHIP under 1.20 seems to be a good place to start when attempting to predict rookie potential.
  • Quality and depth of a pitcher’s repertoire does seem to have great importance. Their fastball must be around league average in terms of runs above replacement, but it must be accompanied by an effective secondary out-pitch that is thrown with moderate frequency (here noted as at least 10 percent of the time).

What does this mean for Brian Matusz?

We’ll start with the guy I’m taking a chance on, Brian Matusz. He had a 1.05 WHIP in the minors, and while we didn’t find a K:BB trend in the limited data, it’s worth noting his was a stellar 3.78. I’d say that can’t hurt. As for his repertoire, the following comes from his scouting report:

His slightly above-average fastball touches 94 mph while his curve and slider are both outstanding. He also throws an above-average changeup. He knows how to pitch and has the ability to throw all four pitches for strikes.

Also, in limited time last season with Baltimore (44.2 IP), Matusz had an extremely effective curveball (wCB/C of 3.66) that he threw 10.6 percent of the time. If his fastball can be league-average, Matusz should have a valuable breakout season.

What about Wade Davis?

Davis has a bit more of a rocky foundation. His minor league WHIP was 1.26, and while that doesn’t preclude his success, it also doesn’t fall in line with our potential indicators. His scouting report had this to say:

A big-time power pitcher with a fastball up to 96 mph, he also commands his plus curve well. A straight change and a new cut fastball are options as well. He’s a great competitor with above-average stuff.

We’ve already seen that “big-time power” doesn’t equal immediate success, but Davis does have a quality secondary pitch. His repertoire isn’t as expansive as Matusz’s, but it should be noted that in 36.1 IP with Tampa Bay last season, Davis had a well-above average fastball (1.73) and curveball (2.66), both of which were his two primary pitches. If he can repeat that type of success, he should have a standout season, but it remains to be seen if he can do it over the long haul.

How does Mat Latos compare?

Latos has similar control to Matusz with an even stronger fastball and a better K:BB ratio in the minors. His minor league WHIP was just 1.06, and he has the ability to reach back for 96+ MPH heat. didn’t have a scouting report on Latos so I defaulted to Jason Grey:

When I saw him at the Texas League All-Star Game last year, I sat next to a veteran scout (and former big league pitcher) who remarked that his heater was “as filthy as I’ve seen.” Latos also has a hard two-plane breaking ball that can be a swing-and-miss pitch, and a developing changeup that’s going to be key to neutralizing lefties.

In his 50.2 innings of experience last season, Latos primarily used an overpowering fastball (66.5%, 0.99 wFB/C) while mixing in an effective curveball (17.6%, 0.83 wCB/C) and the occasional slider (4.1%, 2.16 wSL/C). With such a small sample size it’s tough to know if these pitch values are accurate predictors of future success, but it does show the potential he has. With a rotation spot locked down, he is a definite breakout player for 2010 and probably has the best chance of any rookie if he can stay healthy.

What other rookies are making noise?

Baltimore top prospect Chris Tillman will be starting the season in the minors, but he has an outside shot at a breakout 2010. His minor league WHIP was 1.36 – outside of our predictor range – and while his fastball was below-average in 65 Major League innings in 2009 (-1.62 wFB/C), he did have an above-average change-up that he threw with consistency (0.71 wCU/C). He also had an scouting report:

He’s a big, projectable right-hander with a fastball that runs up to 94 mph and sits comfortably in the low 90s. Also has an above-average curve and a changeup — which has a chance, but lags behind his other two pitches.

Interestingly, his change-up was his most effective pitch while his curveball hovered right under league average (-0.16 wCB/C). Perhaps I am premature in concluding this, but with a high minor league WHIP and a repertoire that could use some development, Tillman doesn’t seem to be ready to become a fantasy-relevant commodity.

Bud Norris is typically the next rookie starter off the board according to ESPN. Norris had a career minor league WHIP of 1.32, higher than our predictor, but he did have an effective slider (1.55 wSL/C) that he threw 36.7% of the time in his 55.2 innings with the Astros last year. This slider is recognized as his most effective pitch, explaining the great frequency with which he threw it. Also according to Jason Grey:

I’ve seen him flash a good enough changeup that it’s a potential plus pitch even though he doesn’t throw it that often. And I have no problem with the Astros first trying to see whether he can develop that third pitch to go with his fastball and slider that will really make him as a starter.

For reference, his change-up was below average in 2009, but Grey believes it has room for development. Again, the lack of a full repertoire (if his fastball and slider aren’t both above-average pitches) and his history of high WHIP limits his 2010 breakout potential.


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Updated: February 1, 2011 — 8:57 pm
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