I know Kittle has played far below his usual standards this season, as he has had 30 yards or less in four of the seven games the Niners have played this season, but I would still keep him in mind, even if he's not their most explosive player at the moment. Kittle has proven he can still be a capable pass catcher and will make your team regret it if they forget about him (just ask the Cowboys and Giants).
Also, after what happened with Derrick Henry and how he went off in the Titans steamrolling of the Bengals, I am not going to let how Kittle has looked so far this season lull me into a false sense of security just for him to go off for 150 yards and three scores. Granted, the Bengals' run defense has been far worse than their pass defense this season, but still.
The Bengals' defense has been middle-of-the-pack against tight ends this season in terms of yardage, however, they are tied for giving up the second most touchdowns to tight ends with four (those scores coming from the Browns, Ravens, Titans, and Cardinals), only behind the Jets at five. If the 49ers decide to utilize Kittle more in the Red Zone and take advantage of the Bengals not having a guy like Tre Flowers there in coverage-- who played a key role against other good or even elite tight ends in previous years-- it could spell trouble for Lou Anarumo's unit.