The Welshman is in career best form after recovering from a broken leg.
Jenkinson told talkSPORT: "He's a friend of mine but I've got a huge amount of respect for him. People forget about the injury he had. It wasn't a long time after [he returned] he had people on his back and was criticised. I always looked at it as very harsh.
"He was a young lad coming back from a bad injury. It was always going to take time for him to find his rhythm again. For the club, the fans and everyone involved with Arsenal it's fantastic to see him playing how he is with freedom and confidence that he has got at the moment.
"It takes a lot of mental strength to pull yourself through those sort of situations. I couldn't be happier for him. In training we've always known what he's been capable of but it's fantastic everyone has seen how good he is this season."