Blake had his highest scoring season ever that year by 14% and it was 34% higher than any season outside of the 1943-1945 seasons when a significant number of players left the league, despite being 32 years old. Carr scored 30% more points that year than he ever did outside of 1943-1945, despite being 34 years old and out of the NHL all together after the next season when he had 14 points total. I'm pretty comfortable surmising that both of them saw their totals inflated by the very weak league they faced.
O'Connor is a bit different case given that he was still in his prime years and he definitely had a superior season in 1948. I'd imagine that it helped that in 1948 he was able to be first line centre rather than Montreal's second line centre, particularly as Montreal's forward depth was worse in 1945 than it had been in his high scoring 1943 season when he played with Drillon (left for WW2) but this example at least shows someone who didn't outperform where you would expect.
As for why these guys didn't put up the same dazzling numbers, I feel comfortable saying that in 1945 Maurice Richard was a better scorer than Toe Blake, Lorne Carr, and Buddy O'Connor were. I certainly think that Blake and Carr, along with Richard, saw an unusual amount of inflation due to the very poor quality of the league though. O'Connor very likely too, but his scoring after 1945 is quite strange.
Not that it's the be all and end all, but when the top players showed up again in 1946 O'Connor's scoring dropped by 50%, Carr's dropped by 71%, Blake's dropped by 25%, and Richard's dropped by 33%. Both O'Connor and Carr played five fewer games and Blake played one more game.