Gonna need to see your definition of hockey sense then, since those two go hand-in-hand in my mind. Decision making with the puck and positioning away from the puck are the two biggest indicators of a player's hockey sense, IMO.
It's much more than that, limiting it to those two is a very simplistic definition.
"Positioning away from the puck" is so much more complex than just saying that.
Watch Marian Hossa play away from the puck. Or Patrice Bergeron. Semin's not in that league in play away from the puck, but he's not far off.
There's a reason he's always had fantastic fancy stats despite never looking like he tries hard. It's because he rarely has to skate hard. You see people praise "effort defensive plays" like backchecks. Lots of the time those are good plays, but very often the only reason those effort plays happen is because someone royally ****ed up and the huge effort is needed to save their bacon.
Great defensive play isn't primarily based on effort. It's primarily based on positioning. If offense is the active state in hockey, then defense is the passive state. Justin Williams is another example I think. He doesn't have a reputation as being great defensively (he certainly has one for being good), but he is. His hockey sense is outstanding and as a result is defensive zone and neutral zone play is good.
I really don't feel the need to defend Semin's offensive hockey IQ. If you legitimately think he has a problem there, you're mistaken. Most of the "poor decisions" he makes now are just because he thinks the game better than the players he's playing with.
Tripp won't shut the **** up about him playing a fast, north-south game, but when he was point per game in 2013 that wasn't the way Semin was playing at all. He was moving through the neutral zone and into the offensive zone exactly the same way he is now. The same deliberation, the same looking through, scanning his options, etc. I think the main difference is confidence in his shot. That would explain why he's shooting less and why he's scoring less. His assists per 60 are barely down from last year.
This summer when I get around to it I'll write a post with video/image/gif examples to show what I'm talking about.