The midfielder made the shock move to Suffolk last summer, joining the Blues for an initial £7.5m. He played an important part in the first derby of the season, a 3-1 win for Town at Portman Road, and thoroughly enjoyed the post-match celebrations.
The atmosphere will be different when he heads back to Norfolk to face his former club this weekend, but McKenna is adamant that he’ll be well aware of what’s to come.
“It’s so obvious to say, of course, when you make a move like that,” he said.
“It’s not going to be popular with the club that you’re leaving behind, but as I said at the time, I can only respect him as a person. He’s come from Chile to try and make the best of his career over in England and that means trying to get to the Premier League.
The midfielder scored the winner for the Canaries when the teams last met in Norfolk (Image: PA)
“He had a couple of good seasons for Norwich and then he made a really big step this year to a club that he felt had a better chance of achieving that goal and it was a step he wanted to make in his career.
“He’s a confident but really humble guy and he wanted to make that step and take it on and I think I give him huge credit for that and I’d say he’s made a really good fist of it so far.
“Of course, us as a team, as a club, him as a player, we know that he’s not going to get a very warm welcome on Saturday because that’s how football works.
“In terms of temperament, there’s not many better than Marcelino so I’ve no worries about him in that regard.”
Nunez is guaranteed to be the subject of abuse from his former fans as soon as he steps out onto the pitch, but will McKenna look to have him wind them up on purpose?
“I’ll give you an honest answer,” he chuckled. “No, I wouldn’t want him to particularly go to the game thinking that he’s going to wind anyone up.
“I’d imagine there’s going to be people already wound up with a match that it is, irrespective of any individual player.
“Everyone who gets the opportunity to play on Saturday needs to be ready for the atmosphere and ready to stand up to what the atmosphere brings.
Nunez was sidelined with an ankle injury in March (Image: Ross Halls)
“In a big atmosphere, it leads to a big intensity, to big challenges. The duels are massively important. The physical bit of the game is massively important.
“It leads to heightened senses, so the composure is really important and the clarity is really important.
“I think everyone who is going to step on the pitch on Saturday needs to be ready for that atmosphere and then ready for what that brings.
“Then the best thing, again, to do is just focus on executing your job and performing as well as you can.
Asked if there have been thoughts about keeping him quiet after the full-time whistle if Town go on to win, McKenna replied: “No. I think we’re so focused on what’s got to come in the 90-plus minutes. We’ll deal with what comes after.”