I think the Reds will, and should, stay pat at the break, outside of maybe stealing Werth if possible, although I think Jonny is good enough to start LF on a playoff team. Cabrera will be fine, his BA will get back to his norm.
The starters are 9 deep. Volquez has nowhere to go but up. When Leake is done, we have a few guys who can replace him. Remember, for the playoffs, you only need 4.
The bullpen has been the best in the league in July, and Jared Burton, Aroldis Chapman, Russ Springer, and Jason Isringhausen are in the wings. They will be the strength of the team in the second half, IMO.
So, what is the key to the Reds surging?
The two first round picks. Bruce and Stubbs will be in RF and CF all season, as they should (lots of talk the last few days of doing something with them.) The key to making the playoffs are how well these two play. Bruce was great at the end of the season last year, as was Stubbs, although those both had special circumstances (injury, callup).
I think if Stubbs and Bruce can be contributors to the team (not necessarily "driving in runs") offensively, this team will go quite far.
I'm happy with Bruce's season to season progression, but I'd also like to see some in-season progression, with him adding some more (not necessarily all) of that power back. If he doesn't and stays with his good AB's and plate discipline, I'm still happy with his season, but I don't think the Reds will be able to pull it off.
Stubbs is Stubbs, and I like him as a player. He has a lot of RBIs, which shows when they're there, he'll hit them in. Obviously the key for him is not K'ing as much. Stubbs doesn't adjust to shorten his swing with two strikes. I love watching Stubbs bat, until he gets two K's, then I don't even watch anymore. If he can just turn a few of those K's to BB's, that will give the best catching duo in the NL a chance to knock in a few more.