I think just grouping Maltsev's issues in the category of 'smarts' is unfair. Maltsev is really good at using his body and reach to create space for himself in a way that I haven't seen out of a Devils prospect in a long time. He's just very bad at using his teammates and this can get him into trouble, especially in the defensive zone. His shot release is also pretty poor.
Wouldn't bet on him playing 200 games in the NHL but he has an interesting collection of skills and if he just gets a tiny bit better, I think he can have a career as a 4th liner, and his skillset seems poorly suited to the KHL, so this might actually happen. Most marginal Russian players return to the KHL, but I'm not even sure he would play regularly for SKA right now.