I think the perception that he raced into form at the Giro is influenced by his crash. He simply had to recover and his peak showed later (also they probably planned a watt bomb on that particular day, saving somewhat in the previous two stages). Let's remember that he already attacked Remco in week 1 on that steep, short climb. As for his form, obviously it's very good right now and will be like that for some time. But intense racing will make it exhaust at some point and there's nothing more intense than racing the Tour (esp. against the two mutants) with Giro in legs.
Something I always considered to be relevant with regards to Roglič is the fact he's
in my opinion a rider who presents form variables based on... confidence.
Like he's much better after he wins because this gives him more belief & confidence... which in turn leads to more wins. The big downside is he eventually runs out of gas. I only mention this because the theory whereby a rested Rog can do better in a GT doesn't always materialize because it reduces his race sharpness & his confidence as well. That's just my impression based on watching him for so long.
So it's a double edged sword, i.e. a well rested Rog will have better form prospects over 3 weeks of racing but he'll lack race sharpness & confidence (this materializes in terms of lacking in positioning & timing, among other little details), whilst a
well raced Rog will have bucket loads of sharpness & confidence but sooner or later the Alto de la Covatilla 2020 happens. I think this is partially why people have often struggled when it comes to analysing his best form & peak power, i.e. because he can produce 'best ever' results when theoretically he should be tired & then conversely he can be a little bit subpar when everyone expects a stomp.
He's like a footballer who plays weekend league games & midweek European matches, i.e. scoring loads of goals & boosted by that confidence. But eventually, a burn out happens. And if he's rested for too long, he goes a little rusty. I realise this is all somewhat contradicted by his traditional early season top level in March but I put that down to more of his high base level manifesting itself as 'superior' to other riders who're just starting their season.
I'm not saying he should do the Tour 2023 or anything based on this analysis either, it's just something I consider relevant.