Gambit are set-up around sh1ro though, and Ax1Le is literally there up close with him, and Jame as the IGL is able to call for himself. It's not like he's also solo-carrying them when Yekindar, Buster, and Qikert are consistently up there (especially Yekindar, and of course not to neglect the excellent supportive role of Sanji). Also sh1ro is relatively not as proven against Tier 1 opposition.
Syrson before the break (BiG had a slump collectively after the break) was leading the team in rating, impact rating, and opening kill rating (attempts + success rate) in almost every event. He's consistently the most impactful AWPer in the top 10, the big three of Zywoo, S1mple, and Device aside. And he also almost exclusively gets kills with the AWP moreso than any other weapon.
I agree Mantuu should be rated lower though.