Defining and identifying Yankee aces

I want to revisit an aspect of last week's post about finding an ace pitcher in the draft. Specifically, how do you statistically define an ace, and how often have the Yankees had one in their rotation?

I think an ace has three qualities. First is durability - knowing that he's going to take the ball each time through the rotation. If your number 1 starter took the ball every fifth game all season, he'd make 33 starts, but I'll set the minimum number of starts to 30 to mitigate the change from the 154 to 162 game schedule and changes in pitcher use. Second is the ability to go deep into games, and give the team innings. I thought about using 220 IP as the benchmark for an ace, but I'll set the minimum number of IP to 200. Third is the quality of the innings. I'll use ERA+, since it adjusts for era and ballpark, and set the minimum ERA+ at 120. For reference, Whitey Ford's 3.04 ERA in 1959 was a 119 ERA+, Ron Guidry's 3.67 ERA in 1987 was a 121 ERA+, David Cone's 3.82 ERA in 1995 was a 122 ERA+, Chien-Ming Wang's 3.70 ERA in 2007 was a 122 ERA+ and CC Sabathia's 3.38 ERA in 2012 was a 123 ERA+. For an ace season, I don't think 30 starts, 200 IP, and a 120 ERA+ are unreasonable standards or expectations. I'll also limit this discussion to the modern, post-World War II era.

According to Baseball-Reference's play index, 28 pitchers meet this criteria, a lot more than I expected. However, only 10 of them had more than one ace season. Ford is the leader with six. Sabathia, Mike Mussina, Guidry, Mel Stottlemyre and Eddie Lopat tie for second with three ace seasons. Roger Clemens, Andy Pettitte, Fritz Peterson and Jim Bouton each have two ace seasons. I'm really surprised that the Yankees have only had six pitchers put up three or more ace-quality seasons in the last 66 years.

If I drop the 30 start requirement and just worry about 200 IP of 120 ERA+, the list doesn't change that much. Ford is still on top, but now with eight ace seasons. Sabathia and Guidry each add one ace season to tie for second with four (in Sabathia's case, all four of his seasons with the Yankees). Allie Reynolds pops up with two ace seasons, and a couple others show up with a single ace season. In either case, the names aren't a surprise, but the number of seasons is lower than what I expected. Why is that?

Ford lost two full years to the Army during the Korean War immediately following 112 great innings as a rookie. In his first 12 seasons after his return, 1953-64 (ages 24-35), his average season was an ace season - 31 starts, 225 IP, and a 134 ERA+. He pitched fewer than 200 innings twice, and had three seasons with an ERA+ worse than 120 (but never worse than 115).

Guidry averaged an ace season for his nine-year prime from 1977-85 (ages 26-34) - 32 games, 29 starts, 222 IP and a 123 ERA+. The strike limited him to 127 IP in 1981, he had good but not great seasons in 1980 and 1983, was closer to mediocre 1982 (104 ERA+), and pretty bad in 1984 (84 ERA+). He didn't stick with the Yankees until he was 26, and after the 1985 season injuries really took their toll.

Lopat averaged an ace season over his first six years with the Yankees - 29 games, 28 starts, 207 IP and a 127 ERA+. However, his 3.65 ERA was a 112 ERA+ in the first season, and injuries limited him to 149 and 178 IP in the last two.

Clemens had seasons of 187 IP (1999) and 180 IP (2002), with a mediocre 102 ERA+ both times. In 2003 he had a good but not great 113 ERA+ in 211 innings. His five seasons with the Yankees was easily the worst stretch of his career, which really speaks to how great he was.

Jimmy Key had an ace season in 1993, was well on his way to another when the strike hit in 1994 and made only five starts in 1995. He was only okay when he came back in 1996, and put up one last ace season with Baltimore in 1997. He had three others with Toronto.

David Cone was both healthy and effective for three full seasons with the Yankees, 1997-99. During those three years he averaged exactly 30 starts, 199 IP and had a cumulative 138 ERA+. He fell five innings short of 200 in 1997 and seven nnings short in 1999. He did average an ace season for his 12-year prime, from 1988-99 (ages 25-36) - 29 starts, 206 IP, 131 ERA+.

As much as everyone loves Andy Pettitte, the dynasty years of 1998-2000 were three of his worst seasons. He took the "L" in almost a quarter of the team's losses in 1998, and was nearly traded. Three of his best ERA+ seasons came in years when injuries limited him to fewer than 150 IP.

Mike Mussina fit the bill in two of his first three seasons with the Yankees (2001 and 2003), helping the Yankees to the pennant both years, and again in his eighth and final season (2008). He missed a fourth ace season in 2006 by three innings. He was okay in 2002, but had three seasons of minor injuries and ineffectiveness as he learned to pitch with diminished stuff.

Mel Stottlemyre's best season was his first, but it included only 96 major league innings. In his first nine full seasons, he never pitched fewer than 251 innings. He had his ace seasons in 1965, 1969 and 1973, plus four more good seasons with an ERA+ between 105 and 117. He only had two bad years in 11 seasons - an 87 ERA+ in 1966 and a 92 ERA+ in 1972.

In Sabathia's first four years with the Yankees, he's averaged 32 starts and 226 innings with a cumulative 135 ERA+. Sounds like an ace to me.

The last three pitchers with two ace seasons all had them consecutively, without much success afterwards - Peterson in 1969-70, Bouton in 1963-64, and Reynolds in 1951-52. Peterson was okay in 1971 before flaming out (91 ERA+ the next 4 years). Bouton got hurt, and was awful in four of the next five seasons, never pitching more than 151 innings. Reynolds was solid and durable, if unspectacular, for the previous four years, and a solid, unspectacular swingman for the next two, which also happened to be his last.

The biggest takeaway for me is that it's pretty damn tough to put up an ace-quality season every single season, even if you are one. If someone can make that level his average over 5 to 10 years, I'd say they're worthy of the name ace, number 1 starter, or whatever other title you want to use.