Is $30MM AAV for a top of the line starting pitcher who nets you 5-6 WAR an overpay when you're getting $6MM / WAR on the deal? It's a 33% discount by some people.
You can't really compare starters to relievers here though. Since the beginning of the game team's have relied on starters to eat up innings and they got paid handsomely for it, as they should considering the best starting pitchers are arguably the most valuable in the game. This reliever strategy however, is so new GM's are jumping on it without fully thinking it through. When the Royals won the WS their team was built around the BP but since they were relied on more than their starters it made perfect sense. However, just because it can work, spending a boat load of money on 1-2 WAR players (Maybe 2.5 at their best) on long term deals is still f***ing dumb. They'll realize that strategy is best used for smaller market teams with weak rotations to gamble more moderately on, there's a reason the name BJ Ryan scares people. Of course there is an argument to be made about the Rickey Romero's, Vernon Wells of the world too but relievers are viewed as more inconsistent & fragile year-to-year than most and the bigger factor is they only get limited innings to build their value. A rough 20 inning stretch can ruin the value of a year's contract.