The Light Blues went into the clash at Hampden Park knowing that victory would have handed them the treble. However, two goals from Anthony Stokes and a stoppage-time winner from David Gray handed Alan Stubbs' men a dramatic 3-2 win.
And with the midfield leaving the defence exposed for the first goal, while the other two goals both came from set-pieces, Warburton appears to be in no doubt that having the 20-year-old available would have made a difference.
"It was a disappointing way to end the season. Hibs won and credit to them but we were 2-1 ahead and I felt we should've seen it out," he told The Scottish Sun.
"Losing Dom Ball through suspension hurt us. We lost that physicality and height he brings."
What will now concern Warburton is the fact that Ball's loan spell at Ibrox has come to an end. So unless the Gers are able to agree some kind of extension with his parent club Tottenham, he will know that he needs to find someone capable of stepping into the youngster's shoes.
While Joey Barton's arrival means that the club are covered in the holding midfield role that Ball was more than capable of playing - as he proved in the Old Firm semi-final - they are in desperate need of some extra options in defence.
Ball's return to White Hart Lane leaves Warburton with just four defenders in the first-team, one for each position, so with the rest of the squad beginning to take shape, he will surely be looking to add reinforcements at the back before too long as the cup final proved that the side could be vulnerable in the Scottish Premiership.