It’s really a matter of passing the eye test.

Donald Brown is running beautifully, recklessly, violently, breaking tackles and gaining hard yards. Trent Richardson is like a magnet around filings, drawing defenders to him like a picnic spread draws flies, getting dragged down and going nowhere fast in the run game.

Which helps me reach two conclusions:

1. The Indianapolis Colts have got to give Brown the majority of the snaps the rest of the season. It doesn’t matter if he starts or not, but he’s got to be their go-to guy more often than not. He’s earned that right after starting the season as the third runner on the depth chart.

2. So far, the Richardson trade has been a bust. The Cleveland Browns got the best of that deal. That’s said with some hesitation; when he was brought here, I wrote he’d be this generation’s Edgerrin James next to Andrew Luck’s Peyton Manning. And I’m not ready to give up on Richardson and say he can’t play, but again, the eye test: It’s been eight games, half a season, and he’s averaged 34 yards on 12 carries per game. He’s hesitating at the hole, unsure when to take the initiative and when to be patient. It’s clear for all to see.

We asked Chuck Pagano on Friday why it seems that Brown consistently gets yards while Richardson continues to be a numbing success of plus-2’s.

“It just seems like there’s times where when we get started and hand Trent the football, we’ve got a couple instances where we either have a mental error up front, we don’t block a guy, there’s somebody free in the backfield,’’ he said. “It just happens to be Trent carrying the ball at the time. I’m not saying that’s always for Trent or that doesn’t happen when Donald is in the ballgame. But again, Trent’s numbers are going to come. He’s a damned good player. He’s a damned good back. He just got here. He hasn’t been here as long as our other guys have been here. And I’m not making any excuses for him. He won’t make any excuses for himself. We’re going to stay patient, and he’s going to have a breakout game. His numbers will increase. His numbers will come. His yards will come.”

And we’ve been hearing this for how long now?

For weeks, there was the argument — and it was a fair one — that Richardson was running out of running formations, running in running situations when the defense could load the box. Brown was running out of more spread formations and doing so in optional pass/run situations when the opponent didn’t always load the box. That largely explained the difference.

But it didn’t explain the difference Thursday night in Nashville, Tenn.

When the Colts took possession of the ball with 7:01 remaining in the game and a three-point lead, everybody in the building, and that included the Titans, knew the Colts were going to run the football. And still, Brown got his yards, resisting the old temptation to take everything outside, waiting behind his blocker, patient and then ultimately violent once he got up into the hole. The Colts gained 51 yards on the ground on that final possession, most of them by Brown.