Found this AP wire today: http://www.philly.com/philly/business/transportation/304536631.html
Mayor Zimmer is right not to be happy, and to be suspicious of PATH's stated motives. Decreasing the frequency from six minutes to seven does indeed decrease the line's throughput and capacity -- by almost 15%, in fact, assuming all else remains the same (same consists, etc.) Given the fact that the trains are already congested, this move will only further increase congestion within New York's largely transit-dependent commute market.
In other words, this move will not increase capacity. In fact, it will only make the capacity problem worse. The rank hypocrisy in the press release is appalling.
There are good reasons for reducing the frequency. The rolling stock might need to be rebuilt; this reduces the trains on hand and so requires frequency reduction. Perhaps the tunnel needs some work. (Though that can be done off-peak.) But to judge whether the plan has merit, PATH needs to be transparent.
And in lying, it proves it is not.