Pretty stupid answer since he was already there the previous year. The question is why does he have so much more goals scored than before.
The answer is he was playing only as a winger last year and had just changed clubs, cities, environment. He was always saying he had to learn from the stars like Neymar and Cavani. Now, he is settled, he has the confidence from being a World Champion and he had to play a lot of times as the number 9, either because Cavani was subbed off for being shit or because there were injuries.
He could have more goals i reckon if he were taking penalty kick or free kick (even though, i don't think he is particularly good with FK since he rarely shoot from outside of the penalty area).
He is developing as a sole striker role. He had experience playing winger (from young age) and second striker (at Monaco). However, he still has a lot to improve like the heading, his shooting technique, his passing technique, etc. He was probably more "perfect" last year (in the sense, he was doing just the right things at the right time everytime) but he is much more influencial this year. He has grown to be a leader of the team instead of the young guy coming in.
