Seeing this from the WS perspective, they won't likely be competitive for two years. If the dude can't catch up with a FB, then they out from under the contract in two years, when their window opens. If he is the real deal, then they have him under arbitration for 4 more years. Unlike most FAs, where poor teams get ruined by bad signings, I think this is just the opposite.
A playoff contender can't risk a starting spot, even if they can risk the money. A bad team can.