His targets had been steadily increasing, but earlier in the season, the game scripts allowed Chargers to run the ball and not have to throw. That has changed the last two weeks with closer matchups. The run game (and pass pro) hasn't been great (o-line issues). This means lots of quick passes or catching Keenan as he sneaks across the field short. He also got alot of screens, including the touchdown.
It seems earlier in the season Eddie Royal was used a ton. Defenses had to adjust to that. Royal still looks pretty dang spry, and is a good part of the offense, but my guess is his targets have trailed off some (haven't looked tho).
I also think Keenan had tweaked his groin earlier in the season. He was getting good separation last night.
Deep passes/shot plays are clearly going to Malcolm Floyd or to Gates deep in the seam. That helps open up the underneath stuff for Keenan.
What I liked seeing last night were the 3rd down throws going to him, and except for when he slipped and Rivers was picked, he was very reliable. Also, he doesn't like to go down easily...loved the first catch where rather than going out of bounds, he turns upfield into Talib (I think) and gives him a little pop.
In Fantasy, TDs are very hard to predict, but generally on a good offense, if the targets and touches are there, they should come. I think last night was a good sign for more consistent production from Keenan.