Passing and decision making still a bit off, but I'm sure the pitch played a part on that as well, but what a 3-point-winning well taken goal that was.
20 per game when you're an offensive player who tends to dribble and cross/get assists a lot isn't such a huge deal. Messi lost 24 balls against Valladollid. And 19 against Alaves. Dembele lost 20 against Valladollid, 22 against Alaves.
I'm not too sure what "lost balls" mean here, but if we are talking about dispossession alone, then Dembele is more or less the same as Messi at around 4 dispossessions per game because they tend to possess the ball more.
In fact Messi was dispossessed 6 times against Valladolid.