Since the development of my metric M/IP, there have been many questions and criticisms. The biggest ones are that it is simply DICE with strikeouts removed, which is true. Another one is the question of what it adds to the ability to analyze a pitcher past what ERA+, WHIP, DICE, etc. do. These are both very valid complaints.

As I said in the comments section of the original post on M/IP: "is it such a bad thing that they're similar? When we remove strikeouts from the equation, it's because we're not trying to see how dominant a pitcher is, we're trying to see how 'mistake free' he has been on average. In that sense, I think this metric has enough use on its own to use it in addition to DICE or FIP."

It is with that in mind that I tell you how M/IP is useful in ways that DICE and FIP are not: DICE and FIP can tell you that a pitcher had a good or bad season. What it can't tell you is why. They can give you a formula that tells you how dominant a pitcher has or hasn't been, but not why they've managed to be so dominant. M/IP can do that.

For my first example, (and I may add more later, but soon I have to pack my stuff because I'm getting ready to move.) I'll take New York Mets starting pitcher Oliver Perez.

This example hits close to home with me. As a Pirate fan, I remember watching Perez in 2004 and thinking "how in the hell did we manage to get this guy? He's lights-out!" And he was. At 22 years old, I thought he would be the Pirates ace for years to come. In 2004, Oliver Perez posted what is to this date his most dominant season in the major leagues. He had what, to this day, are his career highs in strikeouts (239, career average of 200), ERA+ (145, career average of 95), WHIP (1.15, career average of 1.42), and innings pitched. (196, career average of 194) He even had 2 complete games and 1 shutout that year.

Just to drive the point home, here is Oliver Perez's pitching line from Baseball Reference for that year:

2004 12 W  10 L 30 G 30 GS  2 CG  1 SHO  196.0 IP 145 H  71 R  65 ER
22 HR  81 BB 239 SO  9 HBP  2 WP  805 BFP  2 IBB  1 BK 2.98 ERA 4.31 League ERA
145 ERA+ 1.153 WHIP

And his 162 game average, also from Baseball Reference:

10 W 12 L 34 G 33 GS  0 CG  0 SHO 194.0 IP  174 H 104 R  94 ER
29 HR 101 BB 200 SO  9 HBP  6 WP  852 BFP  1 IBB  0 BK 4.38 ERA
4.18 League ERA  95 ERA+ 1.425 WHIP

The question: why? Why did a pitcher who is usually slightly below average have such a dominant season? There's usually an easy to point out reason for the fluke in situations like this, but none of them match with Ollie: It's not a small sample size, because he pitched more innings than he ever has. It's not that batters didn't know what to expect from him, because he'd played two seasons before 2004, had 15 and 24 starts, had pitched 90 and 126 2/3 innings, and had done pretty poorly in those seasons. It's not like batters were baffled by him before, and it's not like there was no tape to watch of him. Batters knew what to expect, and he blew their expectations out of the water. You can't reasonably say that he had peaked that season, because he was only 22 years old. When the average major leaguer peaks at 27, he'd have to be one big exception if that were the case.

We could look at Ollie's DICE for those seasons, and that would show us that 2004 was much better than his average season. But that's not what we want to know: we already know 2004 was way above average for him: a quick glance at his 239 strikeouts in 196 innings tells us that. What we have no idea of is why.

However, my metric can tell us that. It can tell us how many "mistakes," on average, Oliver Perez had made both that season and every other season, and what cost those mistakes had on the team. Let's take a look at Ollie's M/IP lines for his career:

2002: 1.15
2003: 1.31
2004: 0.89
2005: 1.62
2006: 1.36
2007: 0.97
2008 (so far): 1.18

As you can see, according to my metric, Oliver Perez usually makes more than 1 mistake for every inning he pitches. However, in 2004 he was a much more mistake-free pitcher than for the rest of his career. Less batters had reached base against Ollie as a result of his own actions, and therefore he was much more dominant. It's reasonable to assume that because he was making less mistakes, he was also striking out more batters, explaining his career high in strikeouts. Also, 2007 was the only year that Perez showed anything even remotely resembling what he had on the ball back in 2004, and that was another year that he kept his mistakes below 1 per inning (though just barely.)

Strikeouts have never been Oliver Perez's problem. He has always punched out plenty of batters. DICE wouldn't tell you that, however. My metric tells you what the reason for Oliver Perez's success in 2004 was: he let fewer batters reach base or hit home runs off of him than ever in his career. Couple that with his usually high strikeout totals, and you had a recipe for a dominant starting pitcher.