It’s clear why Brandon Aiyuk is unhappy with the 49ers. It’s unclear why he wants to play for the Steelers.

The 49ers frustrate Aiyuk because they treat him like the little brother on the team. He’s not a captain, he doesn’t get the same respect that Christian McCaffrey, George Kittle and Deebo Samuel get and the 49ers won’t offer him $28 million per year for his contract extension. They’re sticking at $26 million per year, which is below his market value.

The 49ers think Aiyuk is immature and want to take him down a peg.

Meanwhile, the Steelers want to build him up and have him set the standard and the culture on their team. Their current no. 1 wide receiver, George Pickens, refuses to block. Aiyuk is one of the best blocking wide receivers in the NFL. So he can show the Steelers offense what an All Pro plays like.

In addition, the Steelers head coach, Mike Tomlin, is the opposite of 49ers head coach Kyle Shanahan. Tomlin is a true player’s coach who will make Aiyuk feel special and important. Shanahan plays favorites, and it’s clear Aiyuk is not one of his favorites. Deebo Samuel is his favorite player on the team — they’re dear friends. They talk to each other every day during practice. So Samuel gets treatment and privileges and targets in big games that Aiyuk doesn’t get.

It’s not that the Steelers are offering so much more money than the 49ers or that their offense is better than the 49ers. They simply can offer Aiyuk the respect the 49ers never will give him.