I forgot who it was against, but he absolutely wrestle fucked someone in one of his title defenses. A lot of wrestlers just look to get on top and waste time, and desperately want to avoid getting stood up. Sherk ATTACKED and it wouldn't have mattered if you wanted to stand him up, he'd just get his opponent right back down. But you couldn't even stand him up because he'd always be working anyway, he'd work harder to advance and pummel his opponent than his opponent would work to get back up.
I'd say he's an easy top 10 LW, maybe top 5 if you really want to argue about it. LW doesn't really have that long and deep of a history as some other divisions.
But, he was generally considered a boring fighter. Maybe he was, I watched a handful of his fights and I thought they were good, but maybe his other ones were not so much. He lost some more time with that PED scandal, which so far he's probably the only fighter I've ever seen that seemingly managed to actually prove his innocence. He might have had a year longer if not for that. It's rare that a player gets accused of PEDs and then the fanbase just ignores it, because otherwise that fanbase would have to openly admit it was wrong for jumping to conclusions.
I think if Sherk came in later on, he could have really done more damage at LW and FW, he is closer to FW where he might actually have been able to stand and bang a bit. His boxing was technically sound, but he was just too small to fight with WWs, and even at LW he just wouldn't have the reach and power to really be able to vary his technique up enough to be truly elite. But at FW? Who knows. If Sherk was in his prime, a match against Aldo would have been interesting.