Short answer here: Yes, GM Paul Holmgren should absolutely attempt to acquire Bobby Ryan. The Flyers need defense more than offense, but Ryan is good enough that he's worth going for. There isn't an excess of top-tier defensemen out on the trade block, and Philadelphia has a few good young prospects that could benefit from getting experience now. Erik Gustafsson, Marc Andre-Bourdon and Kevin Marshall are all good young defensemen who can fill in for their depleted defensive unit until Pronger gets healthy.
Ryan is only 24 years old, and was born and raised in Cherry Hill, New Jersey which is a suburb of Philadelphia. Anaheim took Ryan with the 2nd pick in the 2005 NHL Entry Draft, and he's been one of their top forwards for the last couple years. Last season he played in all 82 regular season games and amassed 71 points.
Sources have told ESPN's Pierre LeBrun that the Ducks are listening to offers for Ryan. However he comes with a cap hit around $5.1 million, his contract is for $25 million over the next five years. Some potential names that the Flyers could throw out there to make it work are Scott Hartnell, Braydon Coburn, Jody Shelley, Sergei Bobrovsky, Matt Carle, Danny Briere and Brayden Schenn. None of these players alone could make the trade happen, and it will be a difficult one for Holmgren to pull off. But if we learned anything from this past offseason, it's to never doubt Holmgren's trade-making ability.
Hartnell and Bobrovsky could be the two best options for a deal, but Hartnell has a no-trade clause and Jonas Hiller has been solid, but not spectacular, in net for Anaheim. Schenn would be enticing for the Ducks, but the Flyers probably want to give him more time to develop and see what he can do. The New York Rangers have probably more compatible pieces to make an offer to Anaheim, but Holmgren has a knack for getting deals done.