Top 5 in the league? lol. No. You could maybe make the argument for top 5 wide receivers but even then, likely not. Randy Moss, Calvin Johnson, Vincent Jackson are all more physically gifted than Marshall and that's off the top of my head. D. Thomas from the Broncos is a better athlete as well.
edit: Oh wow you even said past 20 years. What now? Mario Williams, Vernon Davis and Calvin Johnson are likely the most physically gifted players in the NFL today...
edit: Oh wow you even said past 20 years. What now? Mario Williams, Vernon Davis and Calvin Johnson are likely the most physically gifted players in the NFL today...