Just how good is Zack Greinke?

In 2009, Zack Greinke was probably the best baseball player on the planet. He went 16-8 with a 2.16 ERA, held opponents to a .230 batting average and .276 on-base percentage, finished second in the league in strikeouts and allowed zero runs or one run in 18 of his 33 starts. Basically, he had a Justin Verlander year before Justin Verlander -- the only starting pitcher with a lower ERA in the past decade was Roger Clemens of the Astros in 2005 -- and while Greinke won the Cy Young Award, the Royals being the Royals he finished just 17th in the MVP voting.

In three seasons since, he's played for the Royals, Brewers and Angels and gone 41-25 with a 3.83 ERA -- an ERA that ranks 33rd among starting pitchers with at least 500 innings over those years. So, of course, the rumors are he'll receive $150 to $160 million to sign most likely with the Dodgers or Rangers.

OK, that's a little unfair. Nobody really considers Greinke the 35th-best starting pitcher in baseball, but it is fair to ask exactly how good this guy is. And that's where it gets complicated. Here are a bunch of numbers and stats from the past four years. If you don't like numbers and stats, the basic premise is this: Over the past three seasons, his results (ERA) haven't matched his peripherals.

OK, a few notes here:

1. You'll note the difference in valuation between FanGraphs WAR (fWAR) and Baseball-Reference WAR (bWAR). Without getting into a detailed comparison, the basic reason for this is FanGraphs focuses on peripherals (strikeouts, walks, home runs allowed) while B-R focuses on runs allowed.

2. You'll note that Greinke's FIP -- his fielding independent ERA -- has been lower than his actual ERA. That's why he ranks seventh in FanGraphs cumulative WAR from 2010 to 2012, but 31st in Baseball-Reference WAR.

3. His average on balls in play (BABIP) has been consistent -- even in his 2009 Cy Young season -- and that average is a little higher than the MLB average over that span, which has ranged between .291 and .295. Still, we're not talking about a ton of extra hits here. In 2012, the difference between Greinke's .306 BABIP (via FanGraphs) and the MLB average of .293 is eight hits.

OK, a lot of you know this already. That leaves us with this: There's a huge difference between the seventh-best starting pitcher and baseball and somebody more in the 25 to 30-ish range. We're talking an ace versus a No. 2. Certainly, at $150 million, Greinke will be paid like one of the best pitchers in baseball.

Greinke's higher-than-expected hit rate can be attributed, in part, to playing for some poor defensive teams in Kansas City and Milwaukee, but that doesn't fully explain the difference between his ERA and FIP. But maybe this chart does:

We have a three-year pattern where Greinke has pitched as well -- or at least achieved the same results -- with runners on base, and particularly with runners in scoring position. Now, this be a sample-size fluke, another reflection of the defenses behind him, or maybe a sign that he loses something from the stretch in location or stuff. Certainly, the team giving him this huge contract is gambling that his numbers with runners on will regress closer to those numbers with bases empty -- and thus lead to fewer runs allowed.

In digging into the numbers, we can try and isolate what has happened. I noticed a big split on results with his fastball over these three seasons.

Plate appearances ending in fastball, 2010-2012

Bases empty: .267/.318/.416

Scoring position: .323/.419/.498

With the bases empty, Greinke throws his fastball for a strike 55 percent of the time, but with runners in scoring position that drops to 46 percent. For example, you can look at the two heat maps to the right to see how his location differs against right-handed batters. With the bases empty, he pounds the low outside corner and outer edge of the plate and righties hit just .243 in plate appearances ending with a fastball (403 total PAs). With runners in scoring position, his location drifts more often to the inside part of the plate, resulting in a .302 average allowed in 145 PAs ending in fastballs.

Again, with caveats about sample size, there appear to be real factors behind Greinke's issues with runners on base. The above example is just isolated one pitch. Without fastball command, more bad things happen: You fall behind in counts, you're forced to throw more pitches down the middle and so on. There could be other issues going on here: Pitch selection, not challenging hitters enough or something else that could be correctable.

But in shelling out $150 million for Greinke, a team is banking on something better than a 3.50 ERA. And that's aside from the general health risks involved with any pitcher -- although Greinke has been clean in that regard in his career -- and the perception that maybe he doesn't have the mentality to be a No. 1. (The Brewers started Yovani Gallardo over Greinke in the opening game of the 2011 playoffs.) Of course, if he does end up with the Dodgers or Rangers, they have staff leaders already in place with Clayton Kershaw and Yu Darvish.

So just how good is Zack Greinke? Ace? A No. 2 with only five starts of 8+ innings over the past two seasons? A guy who can win another Cy Young Award?