First, note that in my mind, to be overrated, you need to be highly regarded in the 1st place. So with that idea in mind, I have a few controversial ones as well. Please note that I consider these players some of the greatest players of all time - yet its the way people seem to use their careers to argue for their GOAT status that makes them overrated. NOTE: I also believe that there's 2 different GOATS. GOAT in achievements and GOAT in skill (1/2 considering the competition and 1/2 considering the type of ball each man hit).
1. Bjorn Borg- in my top 5 for GOAT for skill and achievements BUT will people please stop using his quitting early as an argument for his greatness? Greatness is increased by being able persevere and one is able to overcome adversity, NOT the other way around. Using his quitting early to say "he would have won x number of Slams if he hadn't" is ridiculous- the continual use of this argument makes him overrated.
2. Rod Laver - #2 for accomplishment GOAT, but outside the top 50 in skill. My reasoning is simple, pro tennis today is on a different level than it was 40 years ago. His accomplishment of 2 calendar Slams is unbelievable and its not his fault that the level of play was lower back them BUT being 5'8 there's no way he could compete today. People didn't train as hard or competitively start as early. I don't hold that against him for accomplishments but when people say he's the GOAT, I really don't think deep down inside they think he would be beat Federer.
3. Roger Federer - #1 in both GOAT categories - only on this list b/c people act like in the future that the game won't move on from even Roger's game. Some kid will see Roger play and emulate him but he will be bigger, stronger, faster and if someone one day has the same amazing tennis IQ and hand-eye coordination, that kid will combine these elements with better equipment tech to hit the ball faster, with more spin, etc. I might be wrong but Federer skillwise has been my GOAT for the past 5 years yet I never thought that his game would NEVER be overtaken.
As a Federer fan, I hate the fact that Nadal has even been mentioned here. Nadal's type of game might be the next evolution of tennis and he plays it well. Is it as beautiful or as varied or as dependent on tennis IQ? No, but it doesn't mean its inferior - the key for Nadal will be whether he is able to dominate the field consistently for years to come, particularly after Federer is no longer in every final. Its too early to say he's the GOAT for achievements but there's promise there b/c I'd say he's top 10 for skill already - lets not kid ourselves, there's no way someone from 20 years ago could handle his pace and his spin, even the current GOAT has shown its so hard to handle.