I think the real trick here is that they aren't relying on a couple of big stars to pull them through. Look at the yankees a couple of years ago, they smoked everyone with players that were just a bit better than average. The trick is that its a "team" sport.
I think they should have kept Johnson. He got ticked because he wanted more money,they told him he had to prove himself. He had proven himself. How many times has he dominated a season with strikeouts? How many Cy young awards has this guy won?
Back problem?? He's still doing good. He still doesn't get many wins, but his team doesn't bat all that well. Heck when the team you're playing only scores 2 runs and you lose it, it's hard to get to many wins.