The Welshman has made a fine start to his loan at Bolton from Swansea City and is out of contract in the summer.
Ian Evatt believes there is more to come from the 25-year-old, who had not played in 12 months for his parent club before his arrival at the UniBol.
There may well be competition for Bolton in the summer should they look to pursue the former Rangers and Cardiff full-back on a longer deal – but Evatt believes both parties will have something to prove to each other in the next few months as the season draws to a close.
“Declan’s a fantastic player,” said the Wanderers boss. “It comes down to that recruitment in January. We’ve lacked that player on the left-hand side all season. But Dec’s come in and made it his own.
“Hopefully we can keep him fit, keep him in one piece and hopefully we can keep him at this club for the long term. That’s what we’re looking to do, that’s what we want.
“But for us to be able to sign players like him, we have to progress and he has to see that progression. So let’s just keep going, keep working hard and let’s see where we end up this season.”
After signing for Bolton in January John said he was looking to use his time at the UniBol to get himself a move in the summer.
“A few people have asked me why I am dropping down to League Two but I see it as an opportunity,” he told The Bolton News. “It’s a chance to get my face back out there, in the shop window.
“I know I can play Championship level at the very least but right now it’s about coming in to do a good job for the gaffer and the rest will take care of itself.”