I would clarify overvalued as being overvalued in terms of public/media perception. No GM will be jumping to trade for Tim Wakefield even if he were younger. Also, saves are definitely up there with wins in terms of terrible stats.
A basic feature of good stats, in my opinion, is that they isolate a player's performance separate from everything that externally affects stats. Some of these externalities can be team, opponent, situations, etc.
Since you brought up saves:
Pitcher A is Joe Nathan, Pitcher B is Francisco Rodriguez. (Stats from 2008)
Rodriguez had 62 saves while Nathan had only 39. But of course the media hyped "K-Rod" as having the best season ever by a closer.
Saves, though, for fantasy purposes are very similar to wins. The difference in my mind however is that saves should be valued slightly higher because the other stats don't differ as much and they don't affect you as much. For instance, in the example above, the extra 23 saves Rodriguez snatched you only came at the price of 68 innings worth of marginally higher ERA and WHIP. In a starting pitcher situation, an extra 5 wins from a lesser pitcher may come with 200 innings of simliar ERA and WHIP differences.
Also, saves are simply more scarce. In the MLB last year, there were 1184 saves accumulated v. 2428 wins. Simply put, it's easier to find wins than saves and therefore, you should pay more for saves than wins (other stats not considered).