A New Way to Measure Strikeout Proficiency
Strikeouts. The out of choice. You don't have to be a stathead or a scout to know that pitchers who record a lot of strikeouts are generally preferred over those who don't. But the $64,000 question is: How do we best measure strikeout proficiency?
Once upon a time, we simply looked at the number of strikeouts. This method is certainly simple, and it has proven to be a good indicator of pitching prowess over the years.
Johan Santana led the majors in strikeouts last year with 238. Jake Peavy led the National League with 216. In the 1960s, mugshots of pitchers like Santana and Peavy would appear on Topps baseball cards honoring the league leaders in Ks.
TOP TEN LEADERS IN STRIKEOUTS
Johan Santana Min 238 Jake Peavy SD 216 Chris Carpenter StL 213 Randy Johnson NYY 211 Doug Davis Mil 208 Pedro Martinez NYM 208 Brett Myers Phi 208 Carlos Zambrano ChC 202 John Lackey LAA 199 A.J. Burnett Tor 198
With the proliferation of computers, we began to crunch numbers and value the rate of strikeouts in addition to the sheer quantity. The stat of choice soon became strikeouts per nine innings (or K/9).
TOP TEN K/9
Mark Prior ChC 10.15 Jake Peavy SD 9.58 Johan Santana Min 9.25 Brett Myers Phi 8.69 Pedro Martinez NYM 8.63 Jason Schmidt SF 8.63 John Lackey LAA 8.57 A.J. Burnett Tor 8.53 Randy Johnson NYY 8.42 Scott Kazmir TB 8.42
Mark Prior, who ranked 12th with 188 Ks in 166.2 IP, led MLB with 10.15 K/9. Interestingly, Prior, Peavy, and Santana were the only pitchers who punched out more than one batter per inning. (For perspective, among pitchers with 162 or more innings, the average number of K/9 was 6.21 last year.)
Strikeouts per nine innings is very effective but strikeouts as a percentage of batters faced is even better. Why? Well, K/9 favors pitchers who face more batters and penalizes those who don't allow a lot of hits, walks, and hit by pitches. To wit, if a hurler strikes out the side but allows a couple of hits and a walk along the way, is he as effective in whiffing batters as someone who strikes out the side in order? The answer is clearly no.
Not surprisingly, strikeouts per batter faced (also known as K/BF, K/TBF or K/BFP) has become an increasingly popular metric among performance analysts the past few years.
TOP TEN K/BATTERS FACED
Mark Prior ChC .268 Jake Peavy SD .266 Johan Santana Min .262 Pedro Martinez NYM .247 Brett Myers Phi .230 Randy Johnson NYY .229 Josh Beckett Bos .228 A.J. Burnett Tor .227 John Patterson Was .226 Chris Carpenter StL .224
Prior, Peavy, and Santana--the only starters who averaged more than a strikeout per inning--also whiffed over 25% of the total batters faced. Prior led the majors in K/BF, striking out almost 27% of the hitters. However, his margin over Peavy narrows considerably because the latter, by not allowing as many hits and walks per 9, faced fewer batters per out than Prior. (Among pitchers with 162 or more innings, the average number of K/BF was .163 last year.)
Chris Carpenter climbs from 16th in K/9 to 10th in K/BF. The Cy Young Award winner allowed only 1.9 BB/9 last year and was 6th in baserunners per 9. Josh Beckett (13th in K/9) and John Patterson (12th in K/9) also make the top ten in K/BF due to the fact that they had considerably better BR/9 than those they replaced (Jason Schmidt, John Lackey, and Scott Kazmir).
Now, just as K/BF is a better gauge than K/9, strikeouts per total pitches is even better yet. In fact, it is the best one of 'em all. Yes, strikeouts divided by total pitches is the single greatest Defense Independent Pitching Stat out there. It measures dominance and efficiency.
Just as striking out the side in order is preferred over getting all three outs via the K regardless of the number of batters faced, a pitcher who strikes out hitters on three pitches is more effective than those who take five or six to get the job done. By definition, he is missing bats a higher percentage of the time and is also more likely to pitch deeper into games and record a greater number of outs than his counterparts.
TOP TEN K/PITCHES
Johan Santana Min .0714 Jake Peavy SD .0684 Pedro Martinez NYM .0683 Mark Prior ChC .0665 Chris Carpenter StL .0627 Randy Johnson NYY .0616 A.J. Burnett Tor .0600 Brett Myers Phi .0599 Josh Beckett Bos .0592 John Patterson Was .0582
Although the top ten in K/pitches (or K/#PIT) is the same as K/BF, the order is slightly different. Santana moves up from 3rd to 1st and Prior drops from 1st to 4th because Johan (3.66) averaged 10% fewer pitches per plate appearance (P/PA) than Mark (4.03).
What does .0714 K/#PIT really mean? That's a good question. In and of itself, that percentage is rather awkward. However, the decimal comes to life if we multiply it by 100. You see, Santana struck out 7.14 batters per 100 pitches last year. Not only do we now get a real number out of this exercise but the standard of measurement is almost exactly the average number of pitches per start during recent years.
The only difference in the list below vs. the one above is that the number shown represents how many strikeouts per 100 pitches. In an era of pitch counts, it may be more instructive to measure starters by the number of K/100 pitches than K/9 IP.
(For context, among those who qualified for the ERA title, the average starter last year threw approximately 98 pitches and completed 6 1/3 innings. The average number of K/100 pitches was 4.44.)
TOP TEN K/100 PITCHES
Johan Santana Min 7.14 Jake Peavy SD 6.84 Pedro Martinez NYM 6.83 Mark Prior ChC 6.65 Chris Carpenter StL 6.27 Randy Johnson NYY 6.16 A.J. Burnett Tor 6.00 Brett Myers Phi 5.99 Josh Beckett Bos 5.92 John Patterson Was 5.82
I thought it might also be fun to take a look at the worst pitchers in terms of K/100.
BOTTOM TEN K/100 PITCHES
Horacio Ramirez Atl 2.62 Jose Lima NYM 2.79 Kenny Rogers Det 2.89 Kyle Lohse Min 2.99 Bronson Arroyo Bos 3.03 Jason Marquis StL 3.09 Carlos Silva Min 3.10 Jason Johnson Cle 3.10 Jamie Moyer Sea 3.12 Josh Fogg Pit 3.14
All of the pitchers on the above list are more renowned for throwing strikes than getting outs via strikes. Carlos Silva is the best example. The man who led the majors in fewest pitches per plate appearance (3.06) was successful because he only walked a MLB-low 0.43/9 IP last year.
Pitchers who strike out a lot of batters tend to be much more effective than those who don't because they allow fewer balls in play (BIP). As a general rule, the more BIP, the more hits and errors. Hits and errors lead to runs, and runs lead to losses.
We have known for some time that strikeouts are the out of choice. The more Ks, the better. We also know that the fewer pitches, the better. Combining high strikeout and low pitch totals is a recipe for success. The best way to measure such effectiveness is via K/100 pitches. This stat can be improved upon by adjusting for ballpark effects.
Unfortunately, I don't have pitch totals for home and road splits. When this information becomes more readily available, we could rank pitchers by ballpark-adjusted K/100 (or K/100+). I believe this stat just might be the best way to measure pitcher dominance, if not overall performance.