Was last season Zack Greinke's career year? Are there signs that John Danks can get even better? Could Jonathon Niese wind up being the Mets' ace by the end of the year? There are a number of pitching stats that can give us insight into these and other burning questions, but one metric in particular -- Component ERA (ERC) -- can tell us a lot about a pitcher's future all on its own.

For those who aren't familiar with the measure, ERC gives us an estimate of what a pitcher's ERA would look like if it were only influenced by the number of balls in play, home runs, walks, hit batsmen and total bases. That filters out any fluctuations that might be caused by a pitcher's defense, bullpen, or his own luck with stranding baserunners. Unlike BABIP, which speaks to future changes in WHIP that could indirectly affect ERA, ERC is an indicator designed to directly address variations in ERA that could occur over the rest of the season.

Below is a series of bar graphs featuring the 15 starting pitchers with the lowest ERC differentials (ERC-ERA). These are pitchers who may have had some misfortune with their defense, bullpen or stranding of runners. The top two pitchers on the list, Jamie Moyer and Tim Wakefield, have had other types of misfortune, as Moyer has suffered a potentially career-ending elbow injury, and Wakefield has been squeezed out of a rotation spot yet again. Further down in the rankings, Bronson Arroyo, Javier Vazquez and Trevor Cahill all have negative ERC differentials of half a run or more, but their ERAs could be adversely impacted by rising BABIP rates. At the very least, each of these pitchers face a threat to their Fantasy value in the form of an escalating WHIP, so none should be considered a buy-low candidate.

The pitchers who appear most due for ERA improvement are Justin Verlander, Greinke and Roy Oswalt. All three have large negative ERC differentials and none have low BABIP rates that portend a flurry of extra base hits to come over their next several starts. Also, they have not been at their best so far this year because of subpar left-on-base rates (LOB). This is especially true for Greinke, whose 68 percent LOB rate is well below his recent norms. To see the four-year LOB trend for Greinke or the other pitchers on this leaderboard, click on the name or bar in the graph and the trend data will appear below. Greinke may not be able to coax his lineup into scoring more runs, but there is no reason why he can't perform more like the Cy Young Award-winning version of himself over the next two months, especially if he gets back to leaving runners on base more regularly.

Craig Stammen also appears to be due for some better times, at least at first glance, but as his LOB trend data shows, he has yet to have success at stranding baserunners as a major league pitcher. As research by Ron Shandler has shown, stranding baserunners can be a skill, rather than just an outcome of random fluctuation. Until Stammen can demonstrate more success with leaving runners on base, we cannot assume that he will improve in this area and be a useful pitcher for NL-only formats with a mid-4.00s ERA. At the other extreme, John Danks has built much of his recent success on his consistent ability to strand runners, so there is room for his 72 percent LOB to rise. He has also been proficient at preventing hits on balls in play, so his low .263 BABIP may not increase by as much as you might expect. Thanks to a career-high ground ball rate, Danks could easily post a sub-3.00 ERA the rest of the way.

Wade LeBlanc and Jonathon Niese head up the list of starting pitchers who appear headed for some serious ERA inflation. As the season has worn on, LeBlanc is allowing more flyballs and, consequently, more home runs, but his ERA hasn't sustained much damage as a result. He is getting bailed out by an 82 percent LOB rate that would look suspicious for any pitcher. Niese has been more effective than LeBlanc, but not so much that we should expect his ERA to remain in the mid-3.00s. Unless he can reduce an 11 percent home run per flyball ratio, it is more realistic to expect Niese to post a 4.00-plus ERA over the remainder of the schedule.

Niese is not the only Met pitcher to enjoy some good fortune. Mike Pelfrey is allowing more contact with each month, which is particularly a problem for a pitcher who historically allows a goodly amount of base hits on balls in play. His .340 BABIP is high enough that we can expect some regression, but given that his career BABIP sits at .320, it could just as easily stay close to its current level. If that happens and his LOB rate drops toward his career norm, we could see Pelfrey's ERA continue the upward climb it's been making over his last several starts.

Cole Hamels has spent much of the season being underrated and underappreciated, due to an unrealistically inflated BABIP rate. In the span of one month, Hamels has repaired his ERA and WHIP, but now his stats look a little too good. One trend that bodes well for the lefty is that he has given up only two home runs over his last six starts. If he can continue to keep the ball in the park, Hamels could sustain his mid-3.00s ERA, even if he allows a few extra baserunners to score by other means. Given his on-and-off struggles to prevent homers, this is not an especially safe bet to make. Save for a disastrous 10-run (five earned) outing against the Pirates last week, Dave Bush has experienced a similar midseason renaissance, but don't buy into it. He has shared all of Hamels' struggles with the gopher ball, but doesn't share his propensity for missing bats.

Finally, as if Mike Leake's owners don't have enough to worry about with his declining effectiveness and mounting innings count, he could also have to contend with worsening luck. His ERC says that we should expect his ERA to be more than three-quarters of a run higher going forward, though the adjustment may not be that severe. He has induced more double play balls in the majors than all but five pitchers, and as long as he continues to keep the ball down, the Reds' solid infield defense can help him to prevent runs.

Glossary
Runs Created per 27 Outs (RC/27) -- An estimate of how many runs a lineup would produce per 27 outs if a particular player occupied each spot in the order; ex. the RC/27 for Miguel Cabrera would predict the productivity of a lineup where Cabrera (or his statistical equal) batted in all nine spots; created by Bill James
Component ERA (ERC) -- An estimate of a what a pitcher's ERA would be if it were based solely on actual pitching performance; created by Bill James
GO/AO -- Ground out-fly out ratio
GB/FB -- Ground ball-fly ball ratio
Batting Average per Balls in Play (BABIP) -- The percentage of balls in play (at bats minus strikeouts and home runs) that are base hits; research by Voros McCracken and others has established that this rate is largely random and has a norm of approximately 30%
Left-on-base rate (LOB) -- Also known as strand rate. The percentage of baserunners that a pitcher allows that does not result in an earned run scoring. The research that established LOB norms and benchmarks was conducted by Ron Shandler. His research established that a certain level of variation in LOB can reflect differences in pitchers' abilities to prevent baserunners from scoring.
Isolated Power -- The difference between slugging percentage and batting average; created by Branch Rickey and Allan Roth
Walk Rate -- Walks / (at bats + walks)
Whiff Rate -- Strikeouts / at bats

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