The Boy Blues came home early from Spain after a 3-1 opening setback against Getafe was followed by a 2-1 loss against Boca Juniors that left City ruing unfortunate circumstances.
Academy coach Sellars said: "Before we went we had a lot of injury problems. We took a young group including five Under-15s, and it was a real challenge for the players who went.
"We also felt we couldn't take any Under-16s because of GCSEs. So with so many key players missing we never expected to win the tournament as we did out in Abu Dhabi.
"The timing wasn't good, but the boys who played will all benefit from the experience. The lads acquitted themselves very well against Boca, who were more experienced and stronger but we gave them a nailbiter."
City's scorers were Devante Cole against Getafe and Juan Ramon against Boca Juniors.