Matt Winkelman gave the brief explanation of this. First, most of these guys are guys who can be evaluated in a year, because they are older players. It's a cattle-call audition for potentially developable pitching talent by an organization which is light on pitching prospects and is spending pitifully little $ in draft or international undeveloped pitching taln.t. Winkelman says some of the guys have already been released after a short audition. I heartily approve of this action (in the absence of a willingness to devote more of bonus pool to pitchers). What is there to lose? The Phillies couldn't do this if it violated roster limits, so clearly it doesn't. There is no shortage of $, employee or hired consultants to work with them this off-season.
If the Phillies didn't think they could profitably evaluate these extra signees and possibly steal at least a chance prospect, then they wouldn't have made these late, almost certainly cheap, signings. It seems smart baseball.
The Phillies will keep the guys they value most and cut others to stay below the DSL roster limit. They will have a new crop of young LA talent after 15 January, but almost certainly not a class as large as this one, almost all of their budget is supposedly going to 3 guys.