So- I'm still having my look-see concerning the statistical run for Harvey in this season. Normally, I try to find some macro-trends to find some insight as to what happened. Before I get to this, I DID find one micro-snapshot-- and it's an absolute shocker.
Thursday, March 14 1963- it's the Rangers' penultimate road game- against the Red Wings. Rangers are playing for nothing but pride at this point- Detroit (presumably) is battling Montreal for 3rd-place in the standings and avoiding the Wales Trophy winner in the first Playoff Round. Detroit takes a 2-0 lead after one... but in the 2nd period, New York manages to catch up at 3-3. Then, the comprehensive collapse. The final score is Detroit 9, New York 4. Doug Harvey is on the ice for ALL EIGHT even-strength goals. [Suppose it's more likely than not that he's was there for the Red Wings' lone power-play marker, as well.]
Even accounting for that stunner, Harvey's second half of 62-63 doesn't seem qualitatively inferior to his first half. Still, probably not a good time to have a "worst-game-of-career" candidate.