I don't think we are worse, possibly equal or better. Our starting rotation will be better. Russ Ortiz/Hampton were God awful. A 1-2 punch of Oswalt/Rodriguez. Roy should bounce back from last year. Plus if Bud can continue from last season he will be a solid #4 behind Meyers who is a decent pickup. Our defense will no doubt be better as well with Tommy, but at the reduction of our offense. I don't think the bullpen will be to effected by the losses of Hawkins/Valverde. Lindstrom/Lyon should be able to hold down the fort. We could be a team with an outside playoff shot in my opinion or a team getting some more nice draft picks.
Bench might be better - but they aren't any better at third. Feliz/Blum/Keppinger are all interchangable. Berkman and Oswalt are both on the downsides of their career, so it's unclear how much improvement we'll see. Berkman wasn't *that* far from his norms. Oswalt has been regressing each of the last 4 years, and with his size, may very well no longer be an ace pitcher. Wandy had a career year and may see some regression (it would be hard to be any better), so any improvement in Oswalt is likely to be countered by some mild regression by Wandy. Defense will be improved. We have no idea what to expect at Manager - the guy has never managed before - though its probably a safe bet it can't be worse than Cooper. Consider also that the Astros way overperformed their expected W-L loss last year. Based on run differential, they should have been 67-95, so they overperformed by 7 games.
On a side note pertaining to the Rangers. I think Vlad will be a very nice signing for them if he can stay healthy. He still put up very nice stats in limited play last year.