Leeds United signed Pierre-Michel Lasogga on Thursday.
Leeds lost Chris Wood in a £15 million deal to Premier League side Burnley last month.
Losing such a player - who scored 30 goals last season - gave United the unenviable task of replacing him but Roofe looked like he was up to the challenge.
The 24-year-old netted four goals in two games as Leeds' central striker - including a hat-trick in a League Cup win over Newport County - but the Whites' recruitment of Lasogga might suggest that Thomas Christiansen wants another option.
Physically, Lasogga, who joined the Elland Road club on a season-long loan from Hamburg yesterday, is a lot more similar to Wood than Roofe is, and Whelan wants the 25-year-old to be the targetman which Leeds lost by selling the New Zealand hitman.
He told talkSPORT, when told that Lasogga would wear Wood's number nine shirt: "Yeah that's the number we needed to replace after losing Chris Wood. Roofe has done fantastically well, scoring four goals in his two games [up front].
"But we need a targetman with the way we're playing at the moment and we need that strength in depth."
Leeds also signed Jay-Roy Grot last week, another striker physically similar to Wood, and of course the injured Caleb Ekuban, so it remains to be seen whether Roofe does have a role to play up front.