He's been underwhelming thus far, particularly after flying out of the gate when he first got here.
The issue is that he signed a substantial extension (to start this fall) after his first season. It was obviously based on the presumption that he'd improve. Instead he got worse.
In year one he put up 14g-44p. In year two dropped to 9g-34p. If he can produce like he did in his first year his new deal will be... OK. If he can improve and be a 50-60p player then it'll be a really solid contract. If he just repeats what he did last year then it'll be a disaster.
The fact that his production pace in his first two years is almost identical to what Sobotka did in his last two years with the Blues is really disconcerting. Lehtera is fine defensively, but he's not close to Sobotka in that regard, and he was supposed to be a guy who could step into our Top 6 in a way that Sobotka never really could. So far that hasn't been the case.
You can see the offensive potential when watching him, but it hasn't translated outside of a good couple months when he first got here. He had offseason surgery last summer, which likely hurt his conditioning, so hopefully he can rebound this year.