Steve Ott or a Penalty Kill?

Steve Ott has been brutal since coming over to the Blues.  No goals, 3 assists.  Minus 12 in 21 games.  It occurred to me that the Blues' Penalty Kill might be better than having Ott on the ice at 5v5.  Lets look at the numbers:

The Penalty Kill has given up 41 goals and scored 6 in 478:37.  That's a net -35.  The penalty kill drops a goal further behind for every 820.5 seconds played.  Conversely, that's -4.4 goals per 60 minutes.

Ott has been on the ice at 5v5 for 254:30.  With him on the ice the Blues have scored 4 goals and given up 16.  Ott drops the Blues a goal further behind for every 1272.5 seconds played.  -2.8 goals per 60 minutes.

So Ott at 5v5 is not worse than the Penalty Kill.  However, Ott is not better than the PK, either.  254:30 of PK time would result in a net of -18.6.  The 95% Confidence Interval is -10.1 to - 27.1.  Ott's -12 is within randomness of -18.6.