In a season where offense is tough to come by, fantasy owners are looking in every nook and cranny and under every rock looking for power. Power hitters can effect three of the scoring categories in one swing of the bat, hence the premium price for it on draft day. The quick and dirty way to find power sleepers has traditionally been to look at players’ Isolated Power score, and find those batters who had a score of .200 or better. However, that is just one way to find your surprise power, because an attractive ISO this time of year may not be sustainable based on other peripherals. Here are a few players that are going to pop up on your ISO radar as you go searching for help.

Alex Avila , Detroit Tigers
 Production from catchers is always lacking, but it seems even worse this season. In the arid desert of catcher stats stands Avila, who is hitting .290 this season with six home runs, nine doubles, and fifteen runs driven in. In less than half of his 2010 plate appearances, he has nearly met his totals in both doubles and home runs. Last season, Avila had a .112 ISO and a nine percent home run to fly ball rate in 333 plate appearances. This season, he has a fantastic .234 ISO, and his home run to fly ball rate has jumped up to 15 percent. His major league career is but 547 plate appearances, old but his career home run to fly ball rate is 13 percent.

Looking at 300 plate appearances is enough sample size to judge that particular ratio, according to the work presented by Tango, Lichtman, and Dolphin in The Book, so it is reasonable to assume Avila’s rate will come down a bit. In fact, if we go back to 2010 to get 300 plate appearances, Avila has hit nine home runs in his last 76 plate appearances which computes to a 12 percent rate. Avila already has six home runs, but he may not hit ten the rest of the way through the season.

Matt Joyce , Tampa Bay Rays
Joyce hit ten home runs in 261 plate appearances last season, yet already has seven in just 156 plate appearances heading into Sunday thanks to an 18 percent home run to fly ball rate. For his career, Joyce has a 15 percent home run to fly ball rate in 731 plate appearances, so the production here is a bit high for him.

Over his past 300 plate appearances, Joyce’s home run to fly ball ratio has been 12 percent, more in line with his overall 2010 effort than his current pace in 2011. A mix of an inflated home run to fly ball rate as well as a .412 BABIP will make it tough for Joyce to sustain his current production in both the power and the average departments, making him more of a sell candidate than a buy candidate at this time.

Russell Martin, New York Yankees
There is nothing like moving from Chavez Ravine to Yankee Stadium to give a hitter a little more confidence. Martin’s ISO over the past few seasons were .116, .079, and .075 with home run to fly ball rates of nine, five, and seven percent, but this season he has exploded. In 129 plate appearances, Martin has eight home runs and a 22 percent home run to fly ball rate along with a .233 ISO.

Yankee Stadium does not get all of the credit here as Martin has hit four home runs on the road and four at home; overall, he has been more productive on the road. He hit six home runs in his first 16 fly balls but has hit just two more home runs in his last 21 fly balls so his rate is already starting to cool off. He is on pace to potentially eclipse his previous season high of 19 home runs (back from 2007), but the early home run binge is looking more like an outlier, meaning he will likely end up with double of what he has right now.

Jeff Francoeur, Kansas City Royals
If you follow the Baseball Prospectus staff on Twitter, or are even somewhat active on Twitter, you have seen enough baseball writers snarking regarding player performance and “The Rapture” that never came to pass this weekend. That said, the fact Jeff Francoeur is on pace to have a career year makes me wonder if that Mr. Caldwell was just off on his dates.

This is the same Francoeur that is playing for his fourth team since the 2009 season, but here he is with 22 extra base hits including eight home runs and a .229 ISO, 40 points higher than anything he has done in previous seasons. In 2005 and 2006, Francoeur had home run to fly ball rates of 17 and 15 percent, but that rate was between seven and ten percent from 2007 to 2010.

This season, he has rediscovered that 15 percent rate, so there are two diverging thoughts in play here. One is that he has done this before and he should be able to do it again while the other thought is that his rate is roughly one-third higher than what he has done in his previous 300 plate appearances. The rest of his metrics are in line with his career norms, so any fantasy undoing Francoeur is going to have will happen if he cannot maintain this home run to fly ball rate.

Curtis Granderson, New York Yankees
If it were not for the Canadian Barry Bonds in Toronto, everyone would be focused Granderson. He now has 16 home runs on the season, and, just like Martin, has done his damage in that category equally at home and on the road. His .341 ISO is staggering, but he was over .200 each of the previous four seasons as well.

Before this season, his highest home run to fly ball ratio was 19 percent, over fewer than 200 plate appearances in 2005. Since then, he has been somewhere between 12 and 15 percent, with a career rate of 13 percent. This season, his ratio has ballooned up to 23 percent, but this is not a new trend. You will recall that he had extra time with hitting coach Kevin Long last year to rework his old approach at the plate, one that left him susceptible to left-handed pitching. Since then, the results have been rather dramatic. If we go back to last season and look at his home run to fly ball rate by month, we get: nine, zero, 13, 10, 15, and 28 percent.

If you combine his final 117 plate appearances from last year with the 186 he has had in 2011, we get a 25 percent home run to fly ball rate, slightly better than what he has done in 2011. Of all of the hitters reviewed in this piece, Granderson’s efforts, in theory, should be the most sustainable given that his current performance is not any kind of flukish short-term success. 

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Will there be a similar column on NL hitters?
I can do that this week. This was an unintentional selection of AL hitters. I had Ike Davis in this original column but Normandin and I decided his injury and smaller sample size of MLB data didn't justify his inclusion.
Looked at this expecting to read about Asdrubal Cabrera.
I think the 2 HRs yesterday pushed him over the 200 benchmark for ISO. That said, his 16% HR/FB rate stands out like me in a kindergarten class photo (I'm 6'4") so I find him a bit more obvious than the others here. I'm guessing people were assuming Granderson and Martin were byproducts of hitting in Yankee Stadium; I know I was surprised by their splits.
Granderson's HRs are a bit interesting in an 'even' way. 8 at home, 8 on the road, 8 vs. lefties, 8 vs. righties.
He has been very symmetrical :)