I'm beginning to think that F1 is really more suited for younger drivers(minds) because they're just more adaptable.
With significant regulation changes along with limited preseason testing, old timers like Ricciardo just doesn't have a chance. Even Hamilton often times end up seemingly slower than George during beginning of the season. I think older drivers with limited seat times just needs more time to adapt? Vettel also didn't look particularly fast compared to Stroll. Alonso is better, but Stroll is still just a talented paid driver... When Alonso was paired with Ocon, he didn't look super fast either.
Sainz is just a super adaptable driver I think. No matter what regulation or which team, he can always managed to get close to the teams lead driver. He has managed to win races in decent cars now, but I think without winning the championship, it'll be hard for him to shake that #2 status.
Anyway, I just think Ricciardo is too slow to adapt and over the years, his confidence is probably shattered which made things worse? Plus, old age is a bitch. I know he's not the oldest driver, but for sure that's a factor even Michael Schumacher couldn't overcome. I think maybe old age caught up with Senna too? The problem with Senna is that he's not likely to fade away like Ricciardo, but he'd rather die trying to get back on top!
If my 'theory' is right, it's likely reason why it's game over for such a proven winner like Ricciardo and I also don't think Hamilton will do well in Ferrari against Leclerc. I still hope I'm wrong though.