Though Julian Gressel worked on the side with a small group of players, away from the larger group during  Monday’s season-opening training session, Atlanta United manager Frank de Boer implied on Monday that it was related to conditioning.

Gressel would like a new contract that pays more than the $133,000 he received in guaranteed compensation in 2019. He has scored 15 goals with 35 assists in MLS regular-season games the past three seasons. De Boer described Gressel on Monday as very important.

“He wasn’t ready for 11 against 11” de Boer said. “The others were here earlier training on a voluntary basis. We wanted to see where is his level. We will integrate him tomorrow.”

For context, de Boer referenced conditioning issues among other things with Darlington Nagbe last season when wasn’t actively participating with the first team during its training camp in Fullerton, Calif. Nagbe had hoped to be traded. After a full season with Atlanta United, Nagbe was traded during the offseason to Columbus.

For more context, this was the first day of training camp and Gressel could train on Tuesday.

De Boer provided some details on more personnel moves made by the team during the offseason:

He said that he is working with Vice President Carlos Bocanegra on the players the team is bringing in. The team has so far traded for fullback Brooks Lennon, acquired midfielder Emerson Hyndman and defenders Patrick NielsenAnton Walkes and Fernando Meza.

De Boer would like a central midfielder, which he said is most important, and a left fullback to challenge George Bello, who he hopes can play as many as 20 games.

01/13/2019 -- Marietta, Georgia -- Atlanta United coaches convene during practice at the team's training facility at the Children's Healthcare of Atlanta Training Ground, Monday, January 13, 2020. (ALYSSA POINTER/ALYSSA.POINTER@AJC.COM)

Credit: Alyssa Pointer

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Credit: Alyssa Pointer

“He knows what I want,” de Boer said. “He’s the guy who pushes the button if he comes or not.”

He said a new environment may be good for Andrew Carleton, who is going to be loaned as soon as a deal can be reached with a team.

De Boer said that centerback Leandro Gonzalez Pirez, who last week was sold to Tijuana in Mexico, wanted a new environment after three years with the team.

Gonzalez Pirez’s daughter was born in Atlanta and he was active with the MLSPA in its negotiations for a new Collective Bargaining Agreement.

“For both sides, it’s good to have new players, new energy in the locker room every three years,” de Boer said. “You have to have that. I said that to Carlos, I want some new players, new energy of course. Nagbe is gone, Leandro is gone. They are fantastic players who contributed to Atlanta United. Other players need to stand up now.”