The Wales midfielder, 25, was confirmed as a Latics player on Tuesday night after he had witnessed the dramatic 3-3 draw with Yeovil at the DW Stadium, in which five goals inside the last 12 minutes denied the hosts a ninth straight victory.
Rosler claimed that the fact the Glovers scored a treble in those closing throes showed just how fatigued some of his squad are. Their fixture list, which has included European trips to Russia, Slovenia and Belgium, will comprise of at least 60 games while they have an FA Cup semi-final date with Arsenal at Wembley next month as they look to defend the trophy they won last May.
That could be just one of a number of titanic games to come for Rosler's side given that they remain in the play-off spots and will almost certainly have to go down that avenue if they are to be promoted back to the top flight.
And Collison, who is not cup-tied for the semi-final, knows all about achieving promotion through the play-offs, having scored twice in the semi-final first leg against Cardiff in 2012 and then starting in the final when parent club West Ham beat Blackpool.
"The injuries we've had in midfield have been well documented," said Rosler, who has lost Ben Watson, Chris McCann and Roger Espinoza to long-term problems recently.
"We need bodies in there, we need players with energy. Until the end of the season now there will be prizes and high tension and we have to have players who can cope with it.
"Getting Jack - he's coming from a Premier League club, he has experience. This season he's played 19 games and to get him for the run-in is great for our squad. It gives us another option and I'm very happy with this."
Wigan's recent run of form has been even more remarkable considering the plethora of injuries they have suffered and James Perch became the latest to go down against Yeovil. He collided with team-mate Callum McManaman early on and despite soldiering on, made way before half-time.
"We are injuring ourselves now," Rosler joked.
"James said he was right but obviously he wasn't. He was limping.
"It was unfortunate for us that we had to make that early substitution because it restricted us in the end from bringing more fresh bodies on. I'm not sure he'll be ready for Saturday, I hope so, but I'm not sure."