As some have pointed out, we have to put numbers and greatness in context. Not just in terms of era, but in terms of population.
Record number of goals or batting average, etc. 80 years ago when only a handful countries/teams took that particular sport seriously helps to boost the perception of great players back then.
Plus, the way each game was played back in that great player's time. Gretz played when NHL didn't have all that clutching and grabbing and play was wide open. Nowadays, D is so tight that it's hard to score half of the 92 goals Gretz scored that one year.
Anyway, perhaps even more important is the number of people in the world that play the game and play on a competitive level.
Footy is by far the most popular sport in the world in participation at casual and serious levels. By the logic of numbers only, the best player in the world at this sport is by definition the best athlete/sportsman in the world. That guy has like a billion other people in the world who dreamed of being the best footballer in the world. That is Messi's competition.
Also you could maybe say the same thing about running to an extent. Everyone in the world has run as fast as they could. However, very few actually take it to the next level and become serious sprinters. Marathon running has way more participation than sprinting but due to the lack of millions associated with pro marathoners, not that many elite athletes will concentrate their efforts on this sport like elite athletes concentrate on team sports like footy where you can get glory and make some serious coin.
The best modern pentathlete has competition of a few thousand (maybe hundred?) pentathletes in the world I would guess. Pentathlon is that olympic sport that includes horse riding, running, swimming, shooting and fencing.
For hockey, the number of players in the world is under 20 million maybe? Baseball under 100 million? Basketball due to ease of access could be a few hundred million. Cricket participation could be greater than hockey, baseball, American football due to India's population alone but the total number of countries taking it seriously is basically 8 to 10.
Anyway, back to the OP's question. I would guess no, Messi won't win the best player of the year award as many times as Gretz. But Messi could be the greater athlete due to his worldwide competition.
BUT... at the same time, Messi is doing this in La Liga with two dominant teams and the rest are "have nots" though Atleti is making a case.
He is scoring boat loads of goals against much weaker competition while being assisted by other world class talents. If he were in the EPL or instance, or Serie A in the 90s, there were far more top level teams closer to his own team to compete against and the talent within that league spread out more.
And we see in the WC and CA that he has to play against teams that are closer in level to his own team and so his goal scoring exploits are more tame. Just like what CR7 has to go through.