Any competition requires grit... regardless of sport or talent level. Seen a lot of talent collapse under pressure and adversity. Happens all the time, actually. And the higher the level of competition you go, the more it depends on grit and the ability to stay focused on the task at hand as well as being able to overcome adversity.
Because the talent and athleticism differences, for the most part are minute. Sure, there are a handful of players that are head and shoulders above the rest at any given time. But more often than not, mentality is the difference between winning and losing. Just ask anybody who has played at a high level and they will tell you the same.