It was thought Coyle would make a huge effort to prize a big-money striker to the DW Stadium, using some of the cash accrued through midfielder James McCarthy's move to Everton at the end of August which brought an eight-figure sum to the club.
However, Coyle departed at the start of December and Rosler does not believe he has been at the club long enough to deduce which players would be a right fit.
He said: "When the manager comes in at the beginning of the December and then three weeks later the transfer window starts, what do you expect?
"The budget is spent in terms of the amount of players we have in. It's a big squad but that was needed because of the European games.
"What (the January transfer window) allows me is it might free up some money on the wage budget to bring in loan players until the end of the season or on a short-term to help us and that is what I'll try to do."
Rosler's first signing at Wigan certainly fitted that bill with Everton defender Tyias Browning arriving on a one-month loan, while Cardiff striker Nicky Maynard could follow this week with Nouha Dicko's exit seemingly imminent after he watched potential suitors Wolves on Saturday.
Hull boss Steve Bruce also revealed earlier this month that Latics had made a firm enquiry for their central defender Jack Hobbs, who is currently on loan at Nottingham Forest, but Rosler insists his focus is trained on the next transfer window after this campaign ends.
"My real first transfer window will be in the summer where we now have five months, six months time to prepare," he added.
"Three weeks to prepare is not enough. The last thing I want to do is to go out now and buy panic buys; that is not needed because we have good players here.
"The last thing we need is that we are making that sort of panic buys and failing, it's very important when we go for permanent deals we put ourselves in a position where we know all about the player and we limit the risk of failure.
"I can't say that in three weeks that I'd be 110 per cent happy having the knowledge to go for long-term contracts at the moment."
- Sports & Recreation
- Owen Coyle
- Dave Whelan