EVERY Blues Netminder has been better than Allen and every one of them has beaten Allen OUT of his job, including Hutton. Hell, Allen rode in the backseat when we won the Cup. He's a glorified backup at best while a player like Moose, if you catch his hot streak right, is unstoppable.
Come on now.
Chad Johnson did not beat out Allen. I wouldn't count Brodeur or Miller either.
Goalies that I'd argue Allen competed against for playing time were Elliott, Hutton, and Binnington. Halak was blocking Allen's path to the NHL and he really wasn't the goalie Allen was competing with for playing time. Elliott was the goalie blocking his path. Even then, Elliott lost his job twice to Allen (lockout shortened 2012-2013 year until Elliott got over the yips, came back, played well, and Halak got hurt before the series vs the Kings leading to Elliott starting) and 2014-2015 (when Allen was playing better down the stretch leading Hitchock to pull a reversal on his own words on who would start vs the Wild).
Elliott really only beat out Allen once in 2015-2016 when Allen went down to injury in the middle of the season before taking a backseat to Moose due to his play.
Allen also had a very solid stretch in 2016-2017 and pretty much won the series vs the Wild by himself and played fine vs Nashville. 2017-2018 Hutton outplayed him AND should have been getting the starter's load down the stretch.
Allen is more athletic than Elliott but is incredibly streaky and is not as reliant on a system D around him to succeed. He did something Elliott didn't do in the POs, which was put up a a 95.6 save % in a series.
I think Allen could go as far as Elliott did in the postseason being a starter, but would not feel comfortable on relying on him for that role, similar to how Elliott wasn't reliable to be a true starter and wore down with the rest of the team in the 2016 WCF.