Looking through Fangraphs (on which you can easily lose an hour without even noticing), the advanced stats seems to suggest that Lackey's got problems with command. He's throwing his fastball 61.5% of the time this year, up from 59.8 and 58.8 in the last two years. He's also not using his slider -- down 4 percentage points to 9.4% -- or his curveball as much, and relying on his changeup more. In otherwords, he's throwing pitches whose destination is easier to determine, rather than pitches where movement makes them a little more difficult to place.
The results, obviously, have been a problem. His Z-Contact % (a stat that measures the percentage of time a pitch in the strike zone is hit) is over 94% -- 6% over league average, and nearly up 8% from last year. His O-Contact% (making contact on pitches outside the zone) is 68.9%, up 9 percentage points from last year.
These numbers would seem to suggest that Lackey's just not placing the ball where he wants. His pitches either aren't able to be controlled (hence the reliance on fastballs), or are not moving enough and are getting hit (hence the increased contact numbers).
Now, can he turn this sort of thing around? Sure. Even if my assessment is right, pitchers are always battling command issues -- maybe he'll just get a better feel for his breaking pitches. Maybe as the weather heats up he'll find and extra MPH or two on his fastball. His splits for his career suggest we're hitting the sweet spot for Lackey -- his best two months are June and July, with career ERAs of 3.42 in each. He tends to slip in August with a 4.36 ERA (it's that damned humidity, you see), but Senor Clutch corrects things in time for September.
Stat-nerd readers -- please use the comments to correct/add to/applaud my understanding of the stats. What am I missing? Are there signs of a turnaround?