Leake right now has given up 26 homers. His current HR/FB rate is 17.8%. In the past 10 years of Major League baseball, only five qualified starters had previously allowed a higher rate during the year. That's out of a sample of at least 1,000.
Now, consider that none of the five had a HR/FB rate the following season within 5 percentage points of their previous year's total.
The point here is that Leake's homers, to some degree, are not a problem that should be considered indicative of his pitching ability. His GB/FB ratio this year is 1.83 (entering into tonight where he's had a 4:1 ratio). The problem isn't giving up too many flyballs, just too many of them are leaving the yard. But again, that's not likely to sustain going forward.
His xFIP puts him at a 3.72 pitcher this year. My hunch is that next season, he'll likely be in that range.