Ryder had the biggest impact. He carried the Habs offense when it was almost non-existing. When Ryder made the team, no one expected he would be good and would be another checking forward. I heard that people were iffy about him getting a roster spot.
Higgins on the other hand, he joined in a season where the Habs decided to inject some rookies. Aside playing good at training camp, Higgins was almost assured a roster spot unless something insane occured. Not to mention, there was no way he was going to clear waivers.