Being in the right place at the right time is actually the most important thing, I'm sure Bobby would score more if he had the luxury to always be at the end of chances, instead his busy playing number 9, number 10, CM and DM all in one game, to our benefit as well, to compare him to someone like Bergkamp after 1999/2000 his goal scoring completely fell off the cliff, didn't matter though cause he did everything so well, and had Henry Pires and Ljunberg to supplement him.
Chances are still falling Firmino's way though; like I said, he's missed 8/10 of his 'big chances' this season. (How that is measured, exactly, I don't know. I'm guessing a chance above a certain xG? Maybe 0.2?)
The Bergkamp comparison is a good one because Firmino reminds me of him in many ways, but Bergkamp's goalscoring fell off because he got old, too. He was 30/31 by 1999/00. Firmino has only just turned 28.
His finishing always seems better when it's instinct and he has to act quickly, which suggests there's work which could be done to improve his one-on-one situations when he has time.