People who say 2019/2015 are nerds or didn't watch him or remember him during Pep/Tito's stint. Messi was at his absolute physical peak from 2010-2013 before his injury in the late 2012/2013. He was on a 21 goal scoring streak, on course to break his 50 goals record, UCL top scorer for 4 straight years.
After his injury, he lost an edge physically and slowly became more of a creator - playing farther away from goal. Also, the board opting to phase out Xavi and Iniesta with players like Arda didn't help either.
Messi was pretty clutch in the UCL(except against Chelsea lol). Scoring in the both finals, semi against Madrid, vs Arsenal, vs Bayern, Comeback against Milan. Pep understood that a player like Messi should be close to opposition's goal as possible.
Yes, he became a smarter, more cultured and perhaps more well-rounded as a Footballer but that little extra burst of acceleration he lost made him easier to contain. With that acceleration, at times there were no answers. The polishing of his game was a direct consequence of his age, wisdom and experience. More complete doesn't mean better.