For the edition of Outside the Box two weeks ago, I took a deeper look into Johan Santana. Instead of using the widely popular K/9, or strikeouts per 9 innings (formula below), I used what I called K/BF, or strikeouts per batters faced. I also told you I would give some context for the stat in the future. Well, the future is now.I will start off by saying that K/BF was slightly stupid. There is an stat already established that is the exact same thing, just only in a much more presentable format. It's called K%. It's the exact same formula (below again) but you take the decimal produced from the division of the K's into the BF and make it a percentage by multiplying it by 100.Really, the difference between the two, K/9 and K%, is very slight. Dividing by Innings Pitched or Batters Faced is what some would call nitpicking. Let me give you a situation that exaggerates the problem with K/9. You have two pitchers, Pitcher A and Pitcher B with the following stats:

Both pitchers have the same number of strikeouts and innings pitched, thus they have the same K/9. However, Pitcher A has faced a significantly more batters in the 100 innings he's thrown because he allows 1.5 baserunners an inning, vs. just the 1 Pitcher B faces. Assuming neither pitcher gets a double play, Pitcher A would face 450 batters and Pitcher B 400, as shown in the table. Obviously that makes Pitcher B's K% better, because he strikes out a higher percentage of batters that he faces.

Read that last line again, "he strikes out a higher percentage of batters that he faces. " Isn't that the purpose of K/9? To show not just the amount of strikeouts, but the efficiency that a pitcher gets them. Obviously a pitcher who strikes out 25% of his batters is better at striking out batters than one who only gets K's 22.2 percent of the time. However, K/9 doesn't show that difference. To K/9, these two pitchers are the same.

So when you're evaluating to pitchers for a trade in your league, K% is clearly the stat to use, if you can find it. Although the flaw in K/9 was apparent in my handpicked example, let's see how different the K/9 and K%'s are for actual pitchers this season. I made the list from pitchers who have at least 125 strikeouts this season, so that is why it ends at the seemingly random number of 43.

Name                Rank    K/9  Rank     K%
Tim Lincecum             1  10.23     1   27.7%
A.J. Burnett             2  10.02     2   26.6%
Ervin Santana            3   9.37     5   23.9%
Roy Halladay             4   9.21     6   23.9%
Dan Haren                5   9.11     3   24.9%
Chad Billingsley         6   9.09     8   23.6%
Javier Vasquez           7   9.00     9   23.4%
Edison Volquez           8   8.95     4   24.4%
Cole Hamels              9   8.88     7   23.7%
Johan Santana           10   8.81    11   22.7%
Ryan Dempster           11   8.64    12   22.5%
Matt Cain               12   8.48    15   21.6%
Ted Lilly               13   8.43    10   22.9%
Brandon Webb            14   8.22    19   21.2%
Zack Greinke            15   8.20    13   21.9%
Ricky Nolasco           16   8.13    17   21.3%
Felix Hernandez         17   8.09    23   20.8%
Randy Johnson           18   8.07    16   21.3%
Jake Peavy              19   8.06    20   21.0%
Josh Beckett            20   7.97    25   20.3%
Oliver Perez            21   7.88    24   20.5%
Cliff Lee               22   7.85    26   20.3%
Gil Meche               23   7.81    30   19.6%
Scott Kazmir            24   7.77    21   21.0%
Andy Pettitte           25   7.76    22   21.0%
Johnny Cueto            26   7.71    14   21.6%
Justin Verlander        27   7.64    18   21.2%
Ben Sheets              28   7.53    28   19.9%
Brett Myers             29   7.50    27   20.1%
Bronson Arroyo          30   7.44    35   18.9%
Ubaldo Jiminez          31   7.44    33   19.5%
James Shields           32   7.43    36   18.7%
Jonathen Sanchez        33   7.34    32   19.6%
Roy Oswalt              34   7.32    37   18.6%
John Danks              35   7.24    29   19.8%
Jered Weaver            36   7.21    34   18.9%
Manny Parra             27   6.99    39   18.1%
Derek Lowe              28   6.91    31   19.6%
Aaron Harang            39   6.84    38   18.5%
Daisuke Matsuzaka       40   6.67    41   17.1%
Jon Lester              41   6.41    42   17.0%
Jair Jurrjens           42   6.31    40   17.3%
Paul Maholm             43   6.28    43   16.9%

As you can see, there certainly is a difference between the order of pitchers based on their K/9 and K% numbers. The best example is probably Gil Meche. When I saw his name before Scott Kazmir's I thought "no way Meche is a better strikeout pitcher than Kazmir." Sure enough, when I took a look over at the K% column, Meche fell 7 spots down, and Kaz went up 3, showing Kazmir is clearly the better strikeout pitcher even though K/9 thinks otherwise.

Yes, I know what you may be thinking. Besides the Kazmir/Meche example, most of the pitchers are only 1 or 2 spots away in ranking for each stat. Though if K% is better, we should be using it, right? Still, most sites show K/9, something I hope will start to change soon. Even if it is just a "marginal revolution", a revolution it still is.

The last thing you'll probably want is the context for each stat, so here it is. League average K% is 17.01%, and K/9 is 6.93.

If you enjoyed this article, let me know!