Actually, we should look at his numbers over his career: 118,146,96,149,118,116,111Savin Hillbilly said:
Those numbers need a bit of filtering, because offense has been declining MLB-wide. But even if you look at wRC+, he's been declining steadily over that period, though more slowly (after the first year) than the raw numbers imply: 149, 118, 116, 111.
So, yes: the record suggests he's already declining. The question is, can he be expected to temporarily turn that curve around, or will it continue (or accelerate)?
To me, those numbers don't reflect a decline but rather that Panda's performance four years ago was unsustainably high. Pablo dropped 30 points of wRC+ because his ISO dropped 60 points; much of this drop is because Pablo had a 16.7% HR/FB rate in 2011, similar to the 2009 season where he had a 14.0% HR/FB rate.
Steamer is projecting him at 120 wRC+, but that projection infers that Panda has underperformed in 5 of his 7 seasons. I don't buy it, I think he's an above-average hitting/slightly below average fielding third baseman, who's hitting profile is more similar to Billy Butler than David Wright.