LONDON — This was going to be the year Daniel Theis climbed the EuroLeague pay scale. At about the time the 6-foot-9 German forward’s agent, Alex Saratsis, was negotiating a free agent contract with the Celtics last summer, offers had been filed by Real Madrid and Maccabi Tel Aviv.

Theis’ two-year contract just expired with Bamberg in Germany’s Basketball Bundesliga, and after playing on his third straight league title team, he was ready for a sizeable raise. Certainly more than the guaranteed minimum deal the Celtics were offering.

“Yes, absolutely,” Theis said on whether he could have made more by simply moving to Spain or Israel. “But I didn’t want to miss my chance.”

That chance had been lingering since the summer of 2014 when Theis played in the Las Vegas Summer League with the Washington Wizards.

His biggest moments included a five-block performance against San Antonio, but what followed against Miami showed the NBA what was possible. Theis was athletic, had uncanny timing for the ball and put those talents to use with a 10-point, 11-rebound, four-block performance.

Other than those two games, Theis didn’t have another block in his five-game appearance. But he left the league with a lasting YouTube moment at the expense of Tyler Honeycutt. Then playing for Miami, Honeycutt slashed off the left wing, elevated with the ball cocked for a tomahawk slam, and was met at the rim by Theis, who, after registering the block, turned to take a satisfied peek at his prostrate opponent while running down the other end.

“It was evident when you watched him play, he’s done it a million times,” said Austin Ainge, the Celtics’ director of player personnel. “He didn’t have to think about it. He was just reacting. You talk to him now and he doesn’t sound like he’s 25. But he jumps like he’s 25.”

However, in July 2014, the timing wasn’t right.

“The Wizards would have brought him to training camp, but he was under contract,” said Saratsis.

Theis returned to Germany, won his titles, was named the EuroLeague’s 2017 Defensive Player of the Year and knew the ultimate opportunity — the NBA — wasn’t going to fade.

“He was always valued in Europe because of his defensive efficiency,” said Saratsis. “A few teams in the NBA saw what he could bring to the table. There were teams in Boston’s division who were interested.”

But for Theis, none seemed like the proper fit. Instead, he waited. Now, just maybe, the right fit found him.

“We watched tape of Theis, and you could see in preseason and training camp how good his hands were,” said Celtics guard Marcus Smart. “For a big, he has great hands, so it’s easy for us to give him the ball, throw it over the top and he can catch it down low. I’m not surprised. We’ve seen it before, foreigners coming over and taking the NBA by storm.”

Patience and growth

Dennis Schröder likes to say he met Theis while skateboarding. In truth, the Atlanta Hawks point guard met Theis the first day he stopped skateboarding. A coach told Schröder that if he wanted to actually do something in sports, he should exchange the wheels for a basketball, and his first day in the gym he immediately noticed the tall, long forward with what Schröder now describes as “athleticism through the roof.”

They were both 14, from towns in Lower Saxony approximately 20 miles apart. Before long, both were on a rapid rise through Braunschweig’s youth system, where Theis’ older brother Frank also played.

Almost from the start, Schröder and Theis set up a kind of hoops laboratory, practicing pick-and-rolls. Theis had a natural instinct for attacking the rim, and his hands were good enough to pull in just about any pass, some of them crazy, that the point guard lobbed or bounced his way.

“I just felt my way through it, especially on pick-and-roll plays I was lucky,” he said. “I’ve been playing with great point guards all of my career. (The chemistry) with Dennis Schröder was there. We started working on pick-and-rolls really early.”

Schröder hit the jackpot when, at 19, he was selected by Atlanta with the 17th pick in the 2013 NBA draft. Theis was under contract to Ratiopharm Ulm, where he was named the best young player in the German League that season. Though Theis was patient, Schröder’s calls from Atlanta told him what he wanted to hear.

“I told him he’d make it, but to take his time,” said Schröder. “I got to see it with Al Horford when I first got here; Daniel is someone who can get to every ball as well. He catches just about everything they throw to him.”

But the timing had to be right. Unlike some young Europeans who make the jump too soon and grow disenchanted when the minutes don’t materialize, Theis was willing to take his time.

“I had some chances, but I wanted to find the right team, the right coach,” he said. “I didn’t want to go to the NBA and become the 15th guy who goes to the D-League and back, the D-League and back. That’s why I chose to stay in Europe last year to improve my game. I wanted the time to be right to find the right team and the right coach.

“Last year there were some my agent was talking to, so this year I heard from some teams also. I don’t know if I should say. Boston has won so many championships. I had won championships the last couple of years, so this seemed like the right team to win one.”

Rising to the occasion

Video from a 2017 EuroLeague game between Bamberg and the Turkish team Darussafaka Dogus went viral after the Celtics signed Theis. Ante Zizic, a Celts 2016 first-round pick, broke down the lane for what he thought was an open dunk when Theis rotated over from the baseline to meet him at the rim. Zizic collected the rebound and was blocked again, and then a third time after rebounding for yet another chance. Theis calmly waited to go up for the rejection each time.

Zizic, traded to Cleveland as part of the Kyrie Irving deal, showed as a 2017 Celtics Summer Leaguer that his offensive side will need years. He has spent this season shuttling between the Cavaliers and their G League affiliate, the Canton Charge.

Theis, on the other hand, has been ready-made.

“I’m not really surprised,,” said Schröder. “He’s on a winning team, too, so that helps him. But they really have to play him because of what he can do on the defensive end. He’s showing he’s ready, and I’m just glad he’s getting his opportunity.”

Indeed, those hands never felt as rewarded as when Theis reported for his first offseason workouts as a Celtic. Now when he rolled to the rim, the lobs and lasers hitting his palms were coming from Smart, Irving and Terry Rozier.

“When we started playing pick-up, and almost everyone had come back, I saw how easy it can be with someone like Kyrie, Terry and Marcus off the pick-and-roll,” said Theis. “They have the ability to score, to find the roller or find the other guys, and that makes it really easy.

“I have fun just screening for them, because I know they’re going to make a play. It makes life so much easier.”