you'll have to excuse the scepticism, that's the kind of thing i'd say when i didn't have the full details of the situation to skim over the stuff i didn't know/wasn't told/don't understand
of course he's not as fast as he was at the end of last year, relative to the rest of the field. for whatever reason, who cares exactly what that is. this is motorsport, there's always some kind of shenanigans or "unfair advantage", depending on who you talk to and how bitter they are about it. every single bloke on the grid has his own side to it, and if you're going to obsess over one drivers side of the story then you should at least seek to find out what the other guys think to balance it out. imo that end of season run flattered arden far more than da costa.
what was impressive about da costa's half season was that he was able to capitalise on having the best car on the grid pretty much every race. this season we've seen vandoorne and sorensen do the same when they've had the best car. nobody seriously thinks da costa is that much quicker than everyone else, unless they're either a really poor journalist, or a really big fanboy.
the only thing you can use gp3 for is proving that someone is very good. using it as a stick to beat someone with is like calling someone stupid because they can't solve a rubiks cube in 2 minutes