Santon, 24, had spent the first half of the season on the sidelines after reinjuring his troublesome right knee in August, but returned to action in last month’s FA Cup defeat at Leicester.
The Italian defender failed to see the pitch again over the following weeks, however, with fellow left-back options Dummett and Haidara keeping him out of the picture.
Returning to former club Inter Milan before the transfer deadline on a season-long loan with a view to a permanent move, Carver has revealed that Santon was growing frustrated with his lack of action, and believes the deal was the best solution for both sides.
“He’s not featured all season – he’d had a problem with his knee,” he said.
“Paul Dummett and Saido Haidara are two guys at left-back in particular who have done really well.
“He was finding it a problem to get in the team. I’ve always said that if you get in the team and do well it doesn’t matter if you are young or a senior.
“Davide got a little bit frustrated with himself because he wasn’t in the team, but the best option was to send him out on loan, and that’s what we’ve done.”
Santon first arrived at Newcastle from Inter in August 2011 for around £5 million, before going on to make 94 total appearances for the club over the next four seasons.
The eight-time capped international was hailed as a future regular for the Azzurri in the past, and he will hope his return to Serie A will help get his once-promising career back on track.