Ghanaian international Wollacott, who has earned eleven international caps for the Black Stars, made the move to Hibernian from English club Charlton during the current transfer window.
Hibernian finished fifth last season in the Scottish Premiership with 52 points and a goal difference of minus two.
Former Scottish international Marshall, who hung up his boots for Scotland a year ago, appeared 38 times last season in the Scottish Premiership for Hibs and conceded 59 goals.
McManus is of the view that Marshall is a quality goalkeeper with an impressive career, but towards the end of the previous season, there were signs that his concentration was wavering.
The former Hibs star believes that Wollacott’s international experience with Ghana highlights his ability to perform at high levels of competition and with his arrival, Marshall can no longer rely on the luxury of being an automatic starter in every match.
“He’s had an incredible career“, McManus wrote in his Daily Record column.
“He’s a fantastic No.1 but every player needs pressure applied to them and Wollacott looks like being the man to do that.
“He’s a Ghana international, so he’s played at a high level and he has not been signed to play second fiddle to anyone.
“That will only help Marshall to raise his level of performance.
“That just wasn’t the case last season.
“There was nobody breathing down his neck, he knew he’d start every week and that’s never an ideal scenario.”
In addition to securing services of Wollacott, Hibernian successfully acquired the talents of another goalkeeper, Max Boruc, who has signed a permanent two-year contract after his stint with Polish club Slask Wroclaw.
