Differentiating Between an MLB Ace and a True No. 1 Starter

Zachary D. Rymer@zachrymerMLB Lead WriterMarch 20, 2013

There are ace pitchers, and then there are ace pitchers.

You know what I mean. There's an abundance of starting pitchers around Major League Baseball who are very good, but only a couple who are better than very good. They're the true No. 1s, and any scout will vouch that they're a very rare commodity.

What's still something of a mystery, however, is exactly what sets a true No. 1 apart from an ordinary ace. We have a pretty good idea of what ace pitchers look like, but the pitchers known as true No. 1s—the guys good enough to lead virtually any staff—seem to bear their titles based on reputation.

There must be a number of things a true No. 1 can do that a regular ace can't. Their actual pitching must be special, and, by extension, their actual performances must be special as well. Perhaps, there's a secret ingredient as well, one thing that helps them stand out from the rest of the pack.

It's time to go searching for answers.

How Do True No. 1s Pitch?

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When you think of an ace, the first thing you probably think of is a guy with a great fastball. You think of a guy who can hit the high 90s and sit in the mid-90s.

That's one way of narrowing it down. There are a lot of guys out there who can touch the high 90s, but relatively few who can sit in the mid-90s. The ability to do that is not widespread.

In fact, a search on FanGraphs for the best average fastball velocities over the last three seasons (minimum 400 innings pitched) yields only 16 pitchers who have averaged better than 93 miles per hour with their heaters (these being fastballs of all types, mind you).

The list includes some noteworthy names. David Price and Justin Verlander are tied atop the charts with average fastballs of 94.9 miles per hour since 2010, and they're followed by guys like CC Sabathia, Felix Hernandez, Johnny Cueto and Clayton Kershaw. Not a bad sixsome, that.

Likewise, a search for the top average fastball velocities from the 2012 season (minimum 150 innings pitched) yields only 15 pitchers who averaged better than 93 miles per hour with their fastballs. And once again, there are some noteworthy names.

Among them: Stephen Strasburg, Price, Verlander, Kershaw and Gio Gonzalez. That fivesome includes three of the past four Cy Young winners, a guy who finished third in the NL Cy Young voting in 2012 and a guy who may have the most electric stuff of any pitcher in baseball.

As impressive as these names are, though, there are a couple obvious problems.

One is that there are plenty more pitchers besides the greats on those two lists. Edwin Jackson and Ubaldo Jimenez are high in the running in the 2010-2012 velocity rankings, and we know they're not No. 1 pitchers. Jeff Samardzija and Matt Moore are high in the 2012 velocity rankings, and we know that they're not No. 1 pitchers either (yet).

As such, it's clearly true that there's a lot more to pitching than having a hard fastball, just as we were all taught very early on in Baseball 101.

The other obvious issue is that Sabathia and Cueto both failed to average 93 miles per hour with their fastballs in 2012, yet Cueto still succeeded to the tune of a 2.78 ERA and Sabathia managed a 3.38 ERA despite serving two different stints on the disabled list.

In Cueto's case, his average fastball velocity didn't dip all that much, as it averaged 92.7 miles per hour in 2012. With it, he was able to compile a 0.85 wFB/C—the amount of runs saved with a certain pitch on a per-100-pitch basis—one of the highest marks in the league. 

Sabathia, on the other hand, had to overcome a bigger drop in both his average fastball velocity and the effectiveness of his fastball. His average heater dropped from 93.8 miles per hour in 2011 to 92.3 miles per hour in 2012. His wFB/C value went from 0.28 in 2011 to minus-0.73 in 2012.

The writing was on the wall that Sabathia had to adjust. Fortunately, he did.

Sabathia took to throwing his hard stuff less often, choosing instead to throw more sliders and more curveballs. He threw these pitches well, as his slider effectiveness stayed steady and his curveball effectiveness experienced a huge jump: from a minus-1.34 wCB/C in 2011 to a 0.93 in 2012.

As a bonus, Sabathia's changeup was also much more effective than usual. He had a 0.28 wCH/C in 2011 and a 1.68 in 2012.

Sabathia's ERA may have risen by 38 points in 2012, but there's one ERA estimator that thinks he was just as good last year as he was in 2011. That would be SIERA, or Skill-Interactive ERA. Sabathia had a 3.14 SIERA in 2011 and a 3.17 SIERA in 2012. They're virtually the same, all because Sabathia was able to use his deep repertoire of pitches to adjust to the declining effectiveness of his fastball.

He's not the only No. 1 pitcher who can vouch for the value of a deep repertoire. Two other contemporary greats benefited from having deep repertoires when one of their favorite pitches suddenly lost its effectiveness.

Cliff Lee's cutter was less of a weapon in 2011 than it was in 2010, and hitters were onto it more than ever in 2012. His cutter posted a wCT/C of minus-0.85, making it easily the most ineffective of his go-to pitches. However, Lee's fastball, curveball and changeup were still well above-average pitches, and he was able to save face with a 3.16 ERA.

Elsewhere, Jered Weaver's slider lost some effectiveness in 2012, going from a 0.96 wSL/C in 2011 to a minus-0.38 wSL/C in 2012. It was all good because Weaver posted the highest wFB/C in the league and solid values with his curveball and changeup as well. The end result was a 20-win season in which he posted a 2.81 ERA and was a strong contender for the AL Cy Young Award.

Refer to the most recent link and you'll see that Price, the guy who actually won the AL Cy Young, posted excellent values with his fastball, cutter, curveball and changeup. 

Verlander, who finished just behind Price in the AL Cy Young voting, also posted well above-average values with four pitches: his fastball, slider, curveball and changeup.

Felix Hernandez, who finished in the top four in the AL Cy Young voting for the third time in the last four years, also posted well with his fastball, slider, curveball and changeup.

Among last year's elite pitchers, the most curious case is Gio Gonzalez. He got by largely with two pitches, his fastball and curveball. His wFB/C was 1.02, good for a tie for third-best in baseball, and his wCB/C was 1.54, good for 10th in baseball

Nothing should be taken away from Gonzalez's heater and hook; they're both excellent pitches. But they'd been his bread and butter for two full seasons before 2012, yet he never had a season like the one he had in 2012. What made those two pitches suddenly so much more effective?

It had to do with something that all No. 1 pitchers must possess: command.

Up until 2012, the book on Gonzalez was that, while his stuff was great, he generally had no idea where it was going. That changed last year.

Per Baseball-Reference.com, Gonzalez went from throwing 60 percent of his pitches for strikes to throwing 62 percent of his pitches for strikes, which is a lot of strikes over the course of a 32-start sample size. By far the biggest change was Gonzalez's first-pitch strike percentage, which soared from 53 percent in 2011 to 59 percent in 2012.

Getting ahead in the count and throwing strikes more often paid off. Gonzalez upped his strikeout percentage from 22.8 percent to 25.2 percent and decreased his walk rate from 10.5 percent to 9.3 percent. Fewer walks and more strikeouts helped him achieve a career-best 2.89 ERA.

Command was what helped Clayton Kershaw establish himself as a No. 1 pitcher as well. The turning point for him was the 2010 season, when he threw over 200 innings for the first time and compiled a 2.91 ERA and what was then a career-best 9.6 walk percentage.

According to Baseball-Reference.com, that season saw Kershaw up his strike percentage from 61 percent to 63 percent and his first-pitch strike percentage from 55 percent to 60 percent. He's been dominant ever since.

Both Gonzalez and Kershaw can vouch that having total strike percentages over 60 percent and first-pitch strike percentages at least in the neighborhood of 60 percent. So can the 10 guys with the best ERAs in baseball after Kershaw (who tops the ranks at 2.56) since 2010:

Pitcher ERA Strike % First-Pitch Strike %
Jered Weaver 2.73 64 63
Justin Verlander 2.79 66 62
Cliff Lee 2.89 70 69
Roy Halladay 2.91 68 66
Felix Hernandez 2.92 65 62
Johnny Cueto 2.93 63 58
David Price 2.93 65 62
Matt Cain 2.94 65 61
R.A. Dickey 2.95 67 62
Cole Hamels 2.97 66 61

Here we have a collection of the absolute best of the best over the last three seasons in terms of ERA, and all of them are very good at getting ahead of the count and staying ahead of it. It's a fine testament to the importance of command if there ever was one.

Cueto is the shakiest member of the group, but he's getting better in the same fashion of Kershaw in 2010 and Gonzalez in 2012. Last season, Cueto threw 65 percent of his pitches for strikes, and his first-pitch strike percentage checked in at 63 percent (see Baseball-Reference.com).

Most of the pitchers in the above list also pass the repertoire test. We know all about Weaver, Verlander, Lee, Hernandez and Price. Kershaw has always been able to rely on his fastball, slider and curveball, which are consistently good for strong weighted values. No hard evidence is needed to prove that Roy Halladay is in the discussion, thanks to a dangerous repertoire.

Matt Cain, meanwhile, is cut from the same cloth as Halladay. His standardized pitch values show that he's been so successful over the last two seasons, in particular, because he's had three pitches working so well at any given time. In 2011, it was his fastball, slider and changeup. In 2012, it was his fastball, slider and curveball. 

R.A. Dickey and Cole Hamels stand out as anomalies, as neither of them boasts an expansive repertoire. Dickey has his knuckleball, and Hamels' standardized pitch values show that the only pitch he's ever really been able to rely on is his changeup.

These guys can show that very good control and one signature pitch can go a long way. Dickey has turned himself into one of the league's best pitchers by developing an unhittable knuckleball that he commands better than he has any right to, and Hamels' changeup is arguably the best in baseball.

The bottom line is this: If you have either a deep repertoire or a nasty signature pitch and very good command, you have a shot to become a No. 1-caliber pitcher.

Not exactly rocket science, to be sure, but this does narrow things down. If you venture to draw up a list of all the pitchers in baseball with a deep repertoire and/or nasty stuff and sharp command, you won't get very far.

But stuff and command are only good enough to get a pitcher in the No. 1 discussion. To firmly establish himself as a No. 1, an ace pitcher must do the things that are expected of No. 1s, and that's the hard part.

How Reliable Are No. 1s?

It's not good enough for a No. 1 pitcher to feature good stuff and sharp command. A true No. 1 starter will feature these things again and again...and again and again and again.

It's hard to put an exact figure on what sort of ERA a true No. 1 should provide, but it's not hard to narrow down what sort of workload No. 1s are expected to carry. They must rarely, if ever, miss their turn in the rotation, and they must pitch well over 200 innings per season.

That's not easy. According to Baseball-Reference.com, only 11 pitchers have topped 200 innings in the last three seasons. Go back four seasons to 2009, and the number of pitchers who have topped 200 innings each year since falls to seven

So pitching over 200 innings in a season year after year is pretty tough, and true No. 1s have it even tougher. Remember, they're supposed to pitch well over 200 innings per season.

Even going back to 2010, that's an exclusive list. Only 12 pitchers have averaged over 210 innings in the last three seasons. Only six have average over 220. Only two have averaged over 230.

For the most part, the list of 12 pitchers who have averaged over 210 innings per season dating back to 2010 reads like a who's who of MLB No. 1s. Observe:

Pitcher Innings Average IP Per Season
Felix Hernandez 715.1 ~238
Justin Verlander 713.2 ~238
James Shields 680.1 ~227
CC Sabathia 675.0 225
Clayton Kershaw 665.1 ~222
Matt Cain  664.1 ~221
Cliff Lee 656.0 ~219
Dan Haren 650.0 ~217
Jered Weaver 648.2 ~216
David Price 644.0 ~215
Roy Halladay 640.2 ~213
Cole Hamels 640.0 ~213

Here you have seven former Cy Young winners and a couple of guys who are No. 1s by reputation, solid proof of the notion that only the absolute very best can average well over 200 innings per season.

But there's James Shields at No. 3 on the list, which feels...well, odd.

Shields is a very good pitcher, and he passes one of the tests of a true ace by virtue of his 65 percent career strike percentage and career first-pitch strike percentage of 61 (Baseball-Reference.com).

Shields doesn't pass the repertoire test, however, as his track record shows that the only pitch that's ever been consistently effective for him is his changeup. That's Cole Hamels' money pitch as well, but the records show that Shields' changeup has not been as good as Hamels' over the last three seasons. Not even close, in fact.

Yet, there's Shields with 40.1 more innings than Hamels since 2010. Which, again, seems odd.

Shields is a reminder of sorts. His presence in that list goes to show that it's not just the true No. 1 types who can eat tons of innings. Guys like him—very good, but not a No. 1 in a majority of pitching staffs—can eat tons of innings, too.

This leads us to another thing that is required of true No. 1s: They can't just eat innings; they have to eat innings and dominate consistently in those innings. For that, we need something else.

Game score can help. It's a stat that Bill James developed with the idea being to evaluate just how good a given pitcher's start was. It starts at 50 points, and points are added and subtracted based on innings pitched and various outcomes in the pitcher's start. 

Over the last three seasons, a clear upper echelon stands out when looking at the average game scores of pitchers with at least 500 innings pitched. Only seven pitchers have averaged game scores over 60, and they are:

Pitcher Starts Average Game Score
Clayton Kershaw 98 62.4
Justin Verlander 100 62.4
Cliff Lee 90 61.2
Jered Weaver 97 60.7
Roy Halladay 90 60.2
Felix Hernandez 100 60.1
Cole Hamels 95 60.0

For the record, Shields is tied for 18th on the list with an average game score of 55.5, and he'd be even lower if he hadn't averaged a game score of 62.8 in his brilliant (and totally fluky) 2011 season.

Not that Shields should be too hard on himself. Averaging a game score of better than 60 on a consistent basis from season to season is extremely difficult. Of the seven guys in the above table, only Kershaw and Verlander have done it over the last two seasons. 

If you're looking for another reason that Verlander and Kershaw are now viewed as the two best pitchers in baseball, there you go. When they pitch, there's no doubt whatsoever that their starts are going to be good ones. When they pitch, it's a winning day.

Indeed, it's supposed to be a winning day when a No. 1 starter toes the rubber, and we have a stat for that that narrows things down even more: Win Probability Added.

Baseball-Reference.com defines WPA as being sort of like WAR, but with a primary difference being that it takes context into account. That means WPA looks at specific plays and situations, meaning it can help tell us what a pitcher actually meant to his team rather than how good he is compared to other pitchers.

Since 2010, a small handful of elites stands out. Only four guys have compiled WPAs in excess of 10.0 over the last three seasons:

Pitcher WPA
Jered Weaver 11.307
Clayton Kershaw 10.930
Felix Hernandez 10.480
Justin Verlander 10.377

This is the most definitive who's who of true No. 1s in MLB today. Kershaw, Hernandez and Verlander have all won Cy Youngs and are likely to be the three richest pitchers in baseball very soon (Hernandez has that honor all to himself for now). They also bear all the trappings of a true No. 1: deep repertoires and (in their cases) nasty stuff, excellent command, durability and consistency.

So does Weaver, but right now, you're probably asking yourself if he's really more of an automatic winner than Kershaw, Hernandez and Verlander. Weaver satisfies the repertoire/stuff, command, durability and consistency requirements, but...well, really? More automatic than Kershaw, Hernandez and Verlander? There must be something going on.

There is indeed.

Since 2010, there are only a few pitchers in baseball with larger disparities between their ERAs and their FIPs than Weaver. FIP would be Fielding Independent Pitching, which is another ERA estimator that only looks at strikeouts, walks, hit-by-pitches and home runs. Those are the four primary things over which pitchers have the most control.

While Weaver's 2.73 ERA over the last three seasons says he's one of baseball's elite pitchers, his 3.31 FIP says he's very good, but not elite. What's more, SIERA and xFIP—yet another ERA estimator that's adjusted for home runs—agree that Weaver's ERA over the last three seasons should be well over 3.00.

Weaver's not the only No. 1 whose ERA since 2010 doesn't impress the three big ERA estimators. Cueto and Dickey are right there with Weaver. As good as the three of them are, indications are that they've been a little too good.

But they've established themselves as No. 1s anyway. And to be fair, a quick adjustment to the search reveals that the three main ERA estimators frown on Kershaw's, Verlander's and Hernandez's ERAs over the last three seasons as well. The discrepancies are smaller, but they're there.

Herein lies the elusive secret ingredient that a true No. 1 starting pitcher must have. They must have deep repertoires and/or nasty stuff, they must have good command and they must be durable and consistent, but they're not going far without good luck.

A pitcher can expand his repertoire. He can hone his stuff. He can build up his body to be more durable. He can study harder to be more consistent.

Alas, a pitcher who has his eye on No. 1 status can do nothing about becoming more lucky. That's up to the baseball gods. And evidently, they prefer to keep the number of true No. 1s in baseball low.

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