Kelly I believe has indicated many times that he sees Theo as the primary "Big Skill" offensive talent on the team, and that means deadly from the slot position. I'd agree that some wildcat is probably in Kelly's mind---Kelly likes to dabble in that and had Armando early and Hughes middle in a "Leprechaun".
I'd like to throw out some completely dreamt up BS here, having no rumors even to back it up. Kelly seems to really want to put some receiving arrays on the field with real height to them. I think that this is why he likes Daniel Smith [at least in part].
When it looked like Mike Floyd might not come back, I wondered what Kelly would do. Could he occasionally flank Eifert out as a big receiver if Welch is good enough?? In other words have a size-heavy receiving package which would amount to an occasional position-shift for Eifert?? As I say, with Floyd back, maybe not needed.
Another very minor position-shift would be if Shembo can't cover, but we want him to pass-rush. Maybe he is a DE a lot next year. We've certainly seen some very good ones who weighed less than he does. Other than those, I can't see what would motivate Kelly to change anything position-wise.
Last thought: we're pretty loaded at linebacker. If we weren't also three-strong at safety, I'd like to see Danny Spond get a shot back there. He's a terrific athlete, very football-smart as far as I've heard, and with a LB mentality to slobberknock the goo out of receivers. Again, this is not even a rumor.