I think the "it's pre-season and means nothing" caveat should really be a given - I would hope the fans know this by now. So there's that.
I loved Burnett's play - I'm more and more confident about him replacing Bigby while he's out, and perhaps once he's back.
Shields has to make this team - and I'm not talking about that very late interception. I'm talking about a play earlier on, where he was either woefully out of position or had passed the receiver on to the safety - then he pops up and gets his hands on the ball as it's sailing quite some way above his head. I'd love to have seen him catch that ball (that's why he's not a receiver), but the instincts and physical skills to sky up there like that make me positively salivate. Given the solid work he's doing on ST, you have to keep him around to be groomed at CB. I'll be terribly bummed if he doesn't stick.
Zombo was also very impressive. I'm sure he's got some holes in his game at this raw age, but between him and Brad, I'm feeling much better about the OLB position opposite Matthews.
D-line was very nice to watch. Once CM3 is back, that push (and whatever Zombo or Jones, et. al. can do) plus his speed rush is going to be problematic for the other teams' QBs.
It's just a pre-season game, but it's also the one pre-season game anyone puts an ounce of stock in - and they tore Indy up. Great game to watch.