Well I think we can all agree that there isn't deductive entailment such that (Less philosophy applicants active TGC) --> (Less philosophy applicants in general). But it seems like the antecedent at least helps provide a good reason, especially if there is other empirical evidence, for thinking that the consequent might be true.
Having said that, I took a look at TGC forums for philosophy applicants in the 2014, 2013, & 2012 seasons, and it looks like last year's cohort was especially active for some reason. Ultimately, the only way to get reliable empirical evidence would be to get the applicant numbers from the DGS or someone like that, for the Fall 2015 season at the top 50 PGR departments (or at least like 15+ of them).