The 49ers made a major miscalculation.

They thought they could let Dre Greenlaw test his market in free agency and still re-sign him. Maybe they thought he wouldn’t get any good offers because he spent most of last season recovering from an Achilles tear.

Whatever they thought, they didn’t seem to make him a particularly competitive offer. And then the Broncos offered him three years, $35 million with $11.5 million guaranteed, and he accepted it.

Then, according to ESPN’s Adam Schefter, the 49ers called Greenlaw and desperately made him a better offer in hopes that he would back out of his agreement with Denver. He didn’t.

‘The 49ers were trying to get back Dre Greenlaw, even after Denver had an agreement done with him,” Schefter said. “They were pushing to get that done, and they were pushing to flip his decision in this world that we live in where people commit and there are agreements.

“The 49ers tried to flip Dre Greenlaw back to San Francisco, and I think they were pretty persuasive, but not persuasive enough. I think Dre Greenlaw stood his ground and kind of stayed with Denver. … In San Francisco, they’re struggling to pay everybody, so that’s part of it.”

Here’s my interpretation of what happened. Keep in mind this is just my interpretation.

1. The 49ers gave Greenlaw a lowball offer thinking he wouldn’t get anything better. This offended him.

2. The Broncos made Greenlaw feel special and appreciated with their offer in ways the 49ers never have, considering they’ve never paid him or promoted him to the media the way they paid and promoted Fred Warner.

3. The 49ers tried to match the Broncos’ offer at the last minute and Greenlaw told them to kick rocks.

If my interpretation is correct, good for Greenlaw. I hope he succeeds in Denver.

And shame on the 49ers. Instead of signing Greenlaw, they signed Luke Farrell, a blocking tight end, and Kyle Juszczyk, a 33-year-old fullback. That’s how little they valued Greenlaw.

If I were him, I would have left, too.