If Tony Thompson is considered a gate keeper...Carlos Takam needs another couple of fights to cement himself as one. Took Povetkin to the wire as the roider was coming back from his Wlad loss to have another Crack at a title. Removed Tony Thompson from the gate keeper duties in the HW division. Tested out a young prospect named Joseph Parker, who had stepped up from Oceanic level after beating Tupou and Meehan. Was in line to fight Duhaupas before Povetkin called in the Russian cash to tempt him...
Everyone's going to have their own interpretation of what a Gatekeeper is, as the term isn't strictly defined. Personally I'd see a Gatekeeper as a fighter who is an obstacle to overcome to reach the next level, like an end of level boss in a video game. Fighters with the right stuff get past them, but those lacking the vital ingredients (on that night) do not. They either solidify or expose fighters. A great example in the UK was Sergei Khomitsky, who has been the scourge of many British middleweights. He took the unbeaten records of Buglioni and Etches, stopped Jamie Moore, and drew with Nick Blackwell. He put up good losing efforts against John Ryder, Martin Murray and Ryan Rhodes. As his record of 31-14-3 suggests, he isn't genuine world class, but he's tough, well-schooled and dangerous. Good fighters on their game should beat him, but if they're having an off night (or not actually that good) he's the wrong guy to be in the ring with.
He was kicking naz a55 to not come out for the last round iirc Something was not right about that fight imo
I have seen Robert Helenius and I wish he can raise to Gatekeeper status. Not going to bet too much money on that, though.
Salido chisora were first two came mind . Depends on ur definition of gatekeeper Ano salido has won world title but because of the many losses and won't be regarded as a great champion however harsh that may be
Heavyweights Ross purity and Marion Wilson are the two I always appointed as true gatekeepers.. if you didn't get by them, you probably wouldn't achieve championships, if you didn't make big adjustments.
As admitted by himself, Malignaggi became a good gatekeeper towards the end of his career. I don't think it matters if you're an ex champ or not, gatekeeper is someone who sits just below world level.