However, Hill insists he sees the Academy product as a long term fly half for the club and believes this will be the season that he really steps it up.
"I like Joe - he is an exceptionally good player, very talented. I tried him at full-back as an experiment and to give him some game-time," said Hill.
"What we have got with Joe is a genuine talent - when we played Scarlets in pre-season, their coaches were all asking who Joe was. Wherever we go, people can see the raw talent in him.
"Any coach looking at him sees the potential in him and I am convinced we'll get that talent out of him this year."
Hill has also dismissed any concerns of Carlisle's tackling ability and insisted he had all the skills to be a huge success in the playmaker role.
"There aren't many 10s that tackle like Jonny Wilkinson and a lot of clubs hide their 10 on the wing," added Hill. "The likes of Charlie Hodgson and Ryan Lamb - virtually every fly-half in the Premiership - doesn't tackle. Everyone goes at the 10 channel, so Joe's no different.
"Given training and practice, he can and will tackle. That is an area, as with every 10, that you have to work on.
"It is such a multi-skilled position - you have to run the game, pass, goal-kick, line kick, re-start and so on - it is a massive responsibility and sometimes defence is one of the things that comes low on the priority list. We'll get Joe tackling, though, there's no doubt about that.
"We are working on game management and the more he plays the better he will get at that. Make the right decisions at the right time. He has all the skills and now needs to put it together, but he is a hard working lad who will do all he can to achieve his potential."