Nobody is doubting he is the same style of player. It's just, before he used to beat players with ease, often smashing them out of the way as he bulldozed his way to the by-line and delivered a dangerous cross. He completely owned his area of the pitch. These days he rarely beats his man or even tries to, and when he does he can't put a cross on a teammates head if his life depended on it.
There was one moment in the Arsenal game when Gibbs was left exposed at the half way line with Valencia in possession, so he had the entire Arsenal half of space to attack and have a go at Gibbs, but he just stopped and looked for a simple square pass instead, he knew he'd never get past him so he opted to keep possession instead. The Valencia of old would've ripped Gibbs a new bum hole and had their defence on the back-foot.
1 on 1, he isn't the same player. There is nothing tactical about that situation whatsoever.