Craig Mitchelldyer/Portland Timbers

You have to go a long ways back now to remember what the Portland Timbers were before Caleb Porter arrived in the winter of 2012. For their fan support, they were already a revelation. But on the field, they were a non-entity. They hadn't won anything, and they weren't going anywhere. They had no identity.

Porter changed that in a single winter. Forget MLS Cup. Porter's single greatest accomplishment in Portland the work he did in that first offseason.

Bringing in Diego Valeri and Will Johnson helped. But if you want to get a sense of Porter's ability, go back and watch a game from the 2012 season. Then watch the 2013 opener, Porter's first game, against the New York Red Bulls. The difference is stunning.

Though it took Porter five games to get his first win in 2013, that season would continue to set the bar. Porter won Coach of the Year, and the Timbers knocked Seattle out of the playoffs and came within Jason Kreis' final Real Salt Lake team of MLS Cup.

Porter isn't leaving for another job. This wasn't long-planned. Two weeks ago, he was looking ahead to next season with optimism. The best guess is that he's simply burned out. The job, from all outward appearances, aged Porter tremendously. He was unyielding, and so was it.

Most relationships as intense as this one end sooner than they might have. Did Porter have want more decision-making power? Perhaps. There might have been differences over the club's direction. But it's not like he, Gavin Wilkinson, and Merritt Paulson couldn't work together. They did for five years, to great success.

It's more likely that their collective working relationship, along with the unending pressure of coaching in America's most soccer-mad city, took its toll.

This didn't end in fireworks or, so far as we know, in great acrimony. It ended with Porter, in the aftermath of a hugely trying but ultimately successful season, taking a deep breath and walking away. He was worn out. Who wouldn't have been?

In leaving, Porter is betting on himself. There are plenty of coaches in this country who never would have voluntarily left this job. But while Porter wrote that he and his family will "miss the city immensely," and called himself "emotional in thinking about leaving," he just did.

He knows he'll be back. Porter is still a young man. Just 42. He has hundreds of wins ahead of him, wherever he lands next and wherever his career takes him after that.

Whether he — or the Timbers — will ever recapture what they had in these last five years remains an open question. Despite his success on the college stage, Porter broke out here. He and the club were both young when he arrived, and he and the club made their names alongside each other.

Craig Mitchelldyer/Portland Timbers

It wasn't always easy. Porter could be arrogant and condescending. He had to learn during his time in Portland how to take a punch.

But his teams delivered, time and again. Porter is the only successful MLS coach this team has ever had. That's why his departure, aside from the success of the season just completed, was so shocking.

But as Porter said at the championship rally two years ago, life is about memories and moments. He helped bring the Timbers plenty of each.

He put on the club on level footing with Seattle, as he promised he would. He guided two teams to the top of the Western Conference table, and won the club's first and only championship in 2015. If he wasn't planning on being in Portland forever, now was as good a time to depart as any.

The Timbers will survive too. This is very likely the best job in American soccer, and it will attract an excellent array of candidates.

That being said, there are no guarantees when it comes to hiring coaches — and the Timbers will be limited somewhat by their inability to offer potential candidates player personnel power, as the likes of Jesse Marsch and Gregg Berhalter have in their current positions.

When Porter emerged from a field of ten that included Avram Grant back in 2012, he didn't demand that power. It was a lucky thing, because from day one, he had a command of the game and his job that a number of MLS coaches finish their careers without ever obtaining.

With in Porter in charge, it was guaranteed that the Timbers would be competitive. Not necessarily great — the 2014 and 2016 teams ultimately missed the playoffs — but they'd have a chance.

That's high praise for a coach. The rest of the league was in agreement over Porter's abilities. The Red Bulls were interested after they fired Mike Petke in 2014. The LA Galaxy wanted to interview him to fill their vacancy last year.

Porter turned both opportunities down. He wasn't going to leave Portland for another job in MLS. He was, we found out yesterday, just going to leave.

Early in 2016, in the aftermath of the championship, the Timbers signed Porter to a long-term contract extension. He was the guy for as long as he wanted to be.

Press releases announcing contract extensions aren't often particularly interesting. There's the standard praise for the extended party. Hope for the future. Wilkinson said that Porter would be the club's manager "for many years to come."

But Paulson nailed it in that release. “It’s hard to imagine a better cultural, tactical and philosophical fit to lead the Portland Timbers on the pitch than Caleb Porter," he said.

Paulson was right then, and he's right today. It's hard to imagine.

Craig Mitchelldyer/Portland Timbers