The Bermuda international managed just three substitute appearances for the Cumbrians but has gone on to shine for League Two Bradford, with 17 goals to his name this season.
Abbott, who signed Wells from Bermudan club Dandy Town, stressed that he knew the talent the striker possessed but the club could not afford to give him the time necessary to develop.
"We knew Nahki would be a good player and when we sent him to Bradford I begged them to sign him," he told the Carlisle News & Star.
"We said he needed time, another 12 to 18 months, and it was time we struggled to give him here because we needed players to make an immediate impact.
"It's only now that we're seeing a real player developing.
"Those are the risks you take when you let people go. At the time he couldn't get in our first team. He wasn't good enough.
"It would have been very difficult with our finances to pay somebody for two years that wasn't going to play.
"And he didn't (play) for a year after leaving here, either. So we were right at that point. Now he's doing well and good luck to him."
- Sports & Recreation