Kansas City, Mo. ? Alex Smith treads carefully when subject of the San Francisco 49ers is broached. He politely talks about the positive days he spent with them, and then seems to usher along the conversation whenever their divorce is brought up.

After all, he’s with the Kansas City Chiefs now. No need to dwell on the past.

But most would quickly forgive him if he wanted to “stick it” to the 49ers — a phrase he used in a recent interview to refer more generally to his doubters. Smith had San Francisco headed back to the playoffs last season when he sustained a head injury, and when he was healthy enough to return, he found he had lost his job to Colin Kaepernick.

He never got it back as Kaepernick led the 49ers to the Super Bowl.

Now, he’ll get a chance to see many of his former teammates — and show 49ers brass what they discarded — when they visit Arrowhead Stadium for a preseason game tonight.

“Those guys gave me an opportunity, a couple opportunities over the years there,” Smith said this week. “Obviously we disagreed what happened last year, but we move on from it.”

Yes, there will certainly be a mixed bag of emotions when Smith steps on the field, gazes across the line of scrimmage and sees guys such as Aldon Smith and Donte Whitner, with whom he spent so much of his professional career but who are suddenly trying to take off his head.