EI offered fewer AMS rotations last year, so that is the major cause of the drop in figures (in fact available rotations was the largest driver on every route). It's probably more that IAG would prefer passengers to route through LHR. The fare war in Dublin between EI, KL and FR is probably not helping either.
Regardless of what happens, PVD will be down this year, because it didn't operate January to March, while it only missed November and December last year. Also April's passengers will get flown out of Dublin for the time being. I think the expectation is that passengers will be bussed until late April at least.