And Rovers boss Richie Wellens has hinted the Blues failed to get the best out of the ex-Huddersfield man as he wasn't used in his best position at Fratton Park.
The 27-year-old was primarily a bit-part player at Pompey. He was signed after last summer’s transfer window closed to provide cover to centre-forwards John Marquis and Ellis Harrison.
In total, Hiwula scored three times in 15 games, although he made just a solitary League One start.
However, Wellens believes he has recruited a player who's at his best when featuring in a left-wing role rather than through the middle.
And when featuring out wide, the Donny chief reckons Hiwula's capable of being a potent attacking threat.
Wellens told the Doncaster Free Press: ‘He’s a proven performer at this level
‘He’s had 157 starts in his career and 64 goals from the left side and as a striker.
‘We don’t see him as a striker, though he can fill in there.
‘I think his best season came at Coventry under Mark Robins, and they were very good that season.
‘He scored 14 from the left wing and I think he’s very capable of getting double figures from that position for us.’