It’s pretty rare that a top-3 pick gets traded in the early stages of an NFL season, but that’s what happened yesterday when the Cleveland Browns shipped running back Trent Richardson to the Indianapolis Colts.

“He’s a good running back. I don’t know why Cleveland would let go of a guy like that,” said Patrick Willis.

But Richardson couldn’t possibly make an impact on Sunday’s game against the San Francisco 49ers after just two practices with his new team, could he?

TR33“Honestly, I’m not sure. It’s our job to be ready to play whoever’s in the game. So whether he’s in there a lot or it’s (Ahmad) Bradshaw or (Donald) Brown, we have to be ready to play good defense,” Willis said.

That’s the thing, besides Marshawn Lynch the 49ers’ run defense doesn’t have much of a problem stopping anybody. And Richardson, who averaged over 3.6 yards per carry in only five of 17 games with the Browns, hasn’t shown he’s any better than Bradshaw … yet.

Richardson is a talented player, otherwise everyone would’ve roasted the Browns for taking him third overall last year. But with so few reps with his new team and no proof that he’s an elite back so far, the idea that this changes the balance of Sunday’s game seems ridiculous.

But that’s just one man’s opinion. Vic Fangio’s is a lot more important than mine.

“I don’t think (the Colts’ offense) will be different at all. They just may hand it off more than they have been. They got a great running back to give it to. It’s even more reason for them to have balance in their offense, which I think they’re striving to do anyway. So, it just gives them an upgrade at running back and we’re going to see him,” said the 49ers’ defensive coordinator, who also gave a quick scouting report.

“He’s strong. He’s fast. He’s got a good stiff-arm. He’s a move the pile kind of guy, but he also has got some shiftiness too where he can bounce it outside or inside. And he’s comfortable running it inside or outside. They’ve tossed it to him a few times in Cleveland. They have the toss play at Indianapolis and they have a very similar running game at both places, so I think it will be a pretty seamless transition, as much as it can be, for a guy that’s just got there today.”

That’s Fangio telling the Colts that they’re ready for the toss play, so don’t even try. And with Aldon Smith and Ahmad Brooks on the outside and ready, that play probably wouldn’t get much done anyway. Richardson could well be an outstanding player before all is said and done, but this week he provides little more than a distraction from all the stories surrounding the reunion of sorts between Jim Harbaugh and Andrew Luck.

Again, one man’s opinion.

Speaking of Luck, I asked Willis if going against Colin Kaepernick prepares the 49ers for his mobility, and he showed my lack of knowledge with his answer. Duh, I was thinking about training camp, back when practices were open to the media. Maybe I should’ve stuck to Trent Richardson questions.

“We don’t get to go against Kap that much. We go against B.J. (Daniels). He’s just as mobile as any quarterback we feel like we’ll face,” Willis said. “Luck, he’s a guy that doesn’t look like he could be fast, but he runs the ball pretty well … sometimes he doesn’t mind taking the hit. He’s a physical quarterback.”

The 49ers shouldn’t have a problem stopping the Colts’ running game, even with Richardson. The bigger concerns: keeping Reggie Wayne and T.Y. Hilton from beating them downfield, and Luck from gaining yardage on the run.