While Michael Del Zotto has vastly improved his play in his own end of the rink, he has not made as much progress on his offensive game. In fact, if you look at his offensive rate statistics on the Power Play, you'll find that he's actually performing worse per minute than his defensive teammates. He's definitely put up the most points, but these numbers are more indicative of the amount of time he's spent on the PP rather than an advantage he provides over his teammates.

The chart below contains the PP points and time on the ice for all Rangers defensemen who have played more than 15 minutes with the man advantage. Del Zotto's points per minute of power play time is less than all but Ryan McDonagh. And, if McDonagh scores one more point in his next 22 minutes of PP time, he'll also surpass Del Zotto. While MDZ has received more PP time than all of his peers combined, he's put together a rather modest 2.48 P/60 compared with 3.39 for his peers. That point scoring clip is more than 25% behind Defenseman X. Moreover, Del Zotto has accumulated this success rate with the majority of his PP time with the first power play unit, while his peers have played more of their time with the alternates.

If you combine Del Zotto's lower individual scoring rate with the knowledge that Girardi and McDonagh seem to generate more team shots on the PP in their limited time, it's hard to argue against the Rangers trying the D-man alternates at the first unit point to evaluate their options for the playoffs. [For PP shot stats see relative Corsi via behindthenet.ca here].

*All PP TOI and point stats courtesy of NHL.com