Since 2013, his results in stage races before his first GT regressed every single year (single biggest exception being Lo Port). The upside to that was clear as he managed more afterwards. In both 2016 and 2017 he only had one good day before Dauphiné, and that he didn't (prioritise to) have that after doing two doubles back-to-back is unsurprising. By all accounts, he was on track when he got injured.Yeah, he was definitely on the decline. In the spring of 2019, he was barely making the time limit in Catalunya - and that was before his crash. He then did manage to get to a decent level in Dauphiné before he crashed out, but it took him much longer to get there than a few years before.
His absolute peak was maybe back in 2013, but his Giro performances after suffering hardship and then on top to podium the Tour afterwards is nothing to sneeze at.