Online Best>Rush offline it is the reverse.
This is like saying, "The student is excellent in practice tests, but is terrible during the real test!"
If you can't perform consistently under pressure, then it's not really skill.
And it's not like Best is particularly dominant in KCM or Ultimate Battle or anything. He admitted in the Ro24 interviews he was not a true contender to win this season. And he was right.
When someone shows you who they are, believe 'em. I love Best, but he's not a winner. He's a great No 2 or No 3 but you can't have him as your No 1 guy and expect to go anywhere.