Last spring, Ernst Tanner got a lesson in Philadelphia sports fans’ impatience. The Union’s sporting director went to a Phillies game and watched Bryce Harper get booed.

“He was the most expensive player in the whole league, and people were booing him,” Tanner said. Whatever he knew about baseball up to then, he got that much.

When he told Union manager Jim Curtin, the Oreland native was quick to respond: “Yeah, that’s totally normal.”

Curtin didn’t just know because he’s from here. A few miles south of Citizens Bank Park, Curtin was booed for years at Union games when his name was announced with the starting lineup.

But he and Tanner weren’t deterred, and eventually, their work paid off: a first-ever playoff win last October, and now a run to the semifinals of Major League Soccer’s summer tournament that has won wide-ranging praise.

Wednesday’s game against the favored Portland Timbers (8 p.m., FS1 and TUDN) comes just before the two year-anniversary of Tanner’s hiring. So it’s a good time to measure how far the Union have come under his watch.

The team isn’t fully what he wants it to be yet — and winning the tournament won’t make it so — but there has been a lot of progress. Here’s a look at some of the most important benchmarks.

The playbook

In an interview over the weekend, Tanner finally revealed the reasoning behind the Union’s tactical system. When he started here, he spoke about wanting to change the team’s primary formation from a 4-2-3-1 to a winger-less, narrow, 4-4-2 diamond.

Most observers assumed that it was because of his success with the latter system in Europe. In fact, he did it because he wasn’t satisfied with the Union’s depth of wingers.

“Cory [Burke] was playing there and he was kind of alone, not very well-supported all the time,” Tanner said. “I thought it would be a better idea to have at least two strikers to threaten our opponents’ goals.”

Of course, Tanner might not have made the change if he didn’t know what he was bringing in. And the Union haven’t abandoned the 4-2-3-1 entirely. When Ilsinho comes in as a substitute, the team usually switches to that formation, with Ilsinho on the right flank and Brenden Aaronson on the left.

But more than ever, the Union have a clear identity now. They also have the right players to fit it.

» READ MORE: Jamiro Monteiro is the Union’s most important player, even if you don’t always notice him

The newcomers

No player is more emblematic of the Union’s growth this year than defensive midfielder José Andrés Martínez. The position was the front office’s biggest offseason focus, and Martínez was one of two acquisitions for the role.

“The way he was playing [in Venezuela] was totally different, but he showed that natural instinct we were looking for,” Tanner said.

Martínez still was a raw talent when he made his Union debut in March. When the pandemic struck, he went to Miami to live with his agent so that he wouldn’t be stuck in Philadelphia with insufficient support. He put in a lot of work during that time, and Curtin said Martínez “came back understanding the system, understanding what we wanted, understanding the league better.”

On top of that, Curtin said, “Every player, to a man, loves him. They love playing with him, just because he plays with so much passion, so much emotion, and plays so hard in every training session.”

Martínez has struck up a strong bond with Sergio Santos, another of this summer’s most improved players. Santos showed glimpses of his potential last year but needed a lot of time to get used to physicality and fitness levels that were higher than he’d seen before.

“When he first came, I think the training load and what we demanded was a lot for him, and he wanted to work so hard, but it just led to injuries,” Curtin said. “Now he’s in the weight room, he’s taking care of his body every day. He’s so explosive, there’s still going to be little injuries every once in a while, but his ability to play longer minutes now has really improved.”

So has his skill. The breakaway goal Santos scored against Kansas City showed not just his speed, but real class in the deft chip over Sporting goalkeeper Tim Melia.

“Last year he runs full speed and blasts that probably into Melia’s stomach, or tries to kill it and over-hits it,” Curtin said. “To slow down and have the confidence to do something that’s not simple when you’re going that fast, and just dink it over him, that’s a striker’s finish.”

» READ MORE: TV and streaming info, betting odds, and key players to watch in the MLS tournament semifinals

The young phenoms

Roberto Firmino was 19 when Tanner brought him from Brazil to German club Hoffenheim. Naby Keïta was 19 when Tanner brought him to Austria’s RB Salzburg.

Both of those players — now 25 and 28, respectively — are stalwarts of the Liverpool team that romped to England’s Premier League title this summer and won the Champions League last year. (So is Sadio Mané, whom Tanner also brought to Salzburg.)

In recent weeks, Tanner’s phone has lit up over another 19-year-old attacker. As Union fans know well by now, Aaronson has drawn a wave of interest from big European teams.

“Brenden is quite a unique player, and that’s the reason why so many people are very interested in him at this moment,” Tanner said. “If you see his individual creativity; if you see his first touch, which is always going forward; if you see his passing ability and his vision of the game …”

A moment later, Tanner got to what he thinks makes Aaronson really stand out.

“If you look at him close against the ball and the effort he’s putting in against the ball, there are not so many players who can do that,” he said.

Aaronson has played seven games this year for the Union. He’s averaging 1.3 shots, one chance created, 2.5 tackles and a 77.2% pass completion rate. Last year as a rookie, he averaged 1.2 shots, 0.8 chances created, 1.2 tackles, and 80.2% pass completion.

“You know how many teams are playing with a 19-year-old at the No. 10 position, even over in Europe? You don’t find many,” Tanner said. “It tells you everything about him.”

There’s also lots of interest in centerback Mark McKenzie. Last year, he was struck by appendicitis just before he was to captain the United States at the Under-20 World Cup. He doesn’t have as big a stage this year, but he’s showing all of his talents: 2.3 tackles, 3.7 clearances, and 2.4 aerial duals won per game, an 81.1% pass completion rate, and zero cards.

“Some people are judging him by his length [height] as he is not 6-foot-3 or -4,” said Tanner, and indeed, McKenzie is 6-foot. “But he probably jumps higher than everyone with that size, and he’s quicker than everybody. And he has a very stable body.”

» READ MORE: Brenden Aaronson was a star in the Union's quarterfinal win over Kansas City

The manager

Curtin will probably always have his critics, but Tanner isn’t one of them. The two men have built a strong bond, and went to Europe together last winter to visit teams Tanner knows.

“We got to spend a lot of time together, have some good meals, discuss the future of the club, learn from each other, learn also about each other as people,” Curtin said.

That included Tanner learning about Curtin’s political streak, which has come to the forefront this summer. The Union have stood strongly with anti-racism campaigns, and Curtin has helped lead the way.

» READ MORE: Union wear police brutality victims’ names in MLS tournament-opening win over New York City FC

“When we were together over in Europe, I was explaining to him how the situation is over there, and he was explaining to me how the situation is over here,” Tanner said. “He is an honest person and a good human being.”

That is, Tanner said, “the basis of good collaboration, the basis for any communication.” And it was, Tanner said, the first thing wanted to know about Curtin when he started here.

“When I started, that was my first question — what kind of human being is he?” Tanner said.

In the two years since then, he has gotten his answer.

“He’s not only a manager of people,” Tanner said, “he’s a good coach.”