It's not about number of penalties, it's about consistency.
If Boston commits 20 fouls and gets caught 5 times, where the Rangers commit 1 foul and get caught once, would you consider that a good job by the refs?
It's about having and maintaining a set of standards. Not just going by the "flow" of the game, or the time on the scoreboard, or which teams are palying, or who has the loudest home ice fans, how much the team/coaches squawk on the bench, etc.
It's maddening watching games where you have no idea what the refs will and won't call. One game everything is called. The next game, nothing. One period it's tight, third period all hell breaks loose and no calls.
How does the NHL expect to gain and retain new fans when it's nearly impossible to even explain the rules of the game, when long-time fans can't even tell you why a penalty is/isn't called?