Um not so sure about that. Blues shed 4.35M in cap in the trade, and had binnington as the clear #1. IIRC they weren't thrilled about losing him, just couldn't justify that cap hit for their back-up.
But anyways, the point was simply that come playoff time, if you don't have a clear cut #1A goalie, a quality back up is an important asset
I don't recall a post season where so many contenders (oilers, leafs, avalanche) & playoff hopefuls (Canes, flyers, Kracken, Kings, Devils) are dealing with brutally shaky goaltending. Allen would be a net upgrade to the G depth of all those situations... Which isn't to say that I'd want to have my playoff/cup hopes riding on him or the incumbents in any of those situations.
Knights/Hill just showed that getting hot at the right time + "good enough" goaltending behind a well built roster can get you a cup