Fact is that smash was literally always the choice for rag in competitve. Not that rag was ever a popular pick though (very rare). As I said, without smash, there’s little reason to pick rag (well the fun factor is always at play ofc - rag is arguably one of the most fun heroes in the game).
As for ‘stats’? Most ppl can’t hit smash. L2p issues.
Lava wave makes life a lot easier. That’s true. And that’s a fine argument for ppl who don’t like tryharding or are just not in the mood to overthink game flow and are prone to doing macro mistakes. But that doesn’t mean it increases your chance to win. It just alleviates the burden on mistakes you shouldn’t make in the first place.
P.S. Lava wave would be a strong choice for heroes that are inherently terrible at waveclear - that would allow them to (undeservedly) fit a lot more drafts (imagine nova with lava wave). But for rag, who is already at the pinnacle of waveclearing with his base kit? It does very little extra.