SANTA CLARA — Kyle Shanahan has a pattern.

When he’s leading in the second half of big games, he often calls too many passes. He did that in all three Super Bowls he lost, and he did that again on Monday night when the 49ers lost 40-34 to the Detroit Lions.

It was the fourth quarter and the 49ers led by three points. Instead of running the ball and staying balanced, Shanahan called 16 straight passes. The result: Two sacks, one interception, zero points and another humiliating fourth-quarter collapse.

On Wednesday, Shanahan was asked why he abandoned the run against the Lions. Here’s what Shanahan said, courtesy of the 49ers’ p.r. department.

Q: Is there any reason you kind of got away from the run in the second half of the game?

SHANAHAN: “Yeah, because I thought we needed to throw it to win. I think I threw it like 16 times in a row, which I think, I didn’t plan on doing that, but also didn’t plan on having some of those penalties. Got into some second-and-20s, got into, we had a first-and-15, then a delay of a game that went into a second-and-20, then we had a two-minute drive trying to come back down two scores. So I think that’s why it got out of hand. But our plan going into that game was we knew we were going to have to throw it a lot more to win.”

Q: Is that at all related to new offensive linemen, that teaching the new guys the run game is a little harder than pass protection?

SHANAHAN: “To a degree. But it also has to do with how their defense was built. I thought it was easier to get yards throwing the ball than running. And when you’re in a game where you feel you’ve got to score every series, you’re not going to be as patient with something that, I mean, they’re a real good run defense, the way they commit to it. I think they were fourth in the league. Regardless of their injuries, their style of defense is tough to run the ball against. And when you have some different O-Linemen in there, it’s a little tougher to block against. And the combination of that, with what I thought we could do in the pass game, I was going to take the higher percentage plays to attempt to try to score over 40.”

MY TAKE: Shanahan says the 49ers needed to throw the ball to score 40 points and win. But the Lions were able to score 40 and win by staying balanced. They ran 34 times and passed 35 times. And that’s because the Lions offensive coordinator, Ben Johnson, is better than Shanahan.