Multiple NFL executives addressed the issue with ESPN this past week after Lawrence left open the possibility he could return to Clemson next season.
"I'd be shocked if he went back [to Clemson]," one source told ESPN.
"You have a better chance of winning the Boston Marathon than he does of going back to school," another source said.
"Any person in that stratosphere would go, and history tells me he goes out," a third source told ESPN.
Lawrence made headlines this past Tuesday when he said he hasn't ruled out returning to Clemson for his senior year instead of going pro.
But Swinney said two days later that he would "be surprised" if Lawrence, the projected No. 1 pick in the 2021 draft, is back with the Tigers next year.
Lawrence began interviewing potential agents for his NFL career in March, according to league sources, and has been interviewing marketing agents.
Lawrence, who is scheduled to graduate with a bachelor's degree in marketing in December, is 31-1 as a starter at Clemson and is a contender for the Heisman Trophy this season. He did not play in Saturday's victory against Boston College after testing positive for COVID-19 this past week and also will miss top-ranked Clemson's showdown next weekend with Notre Dame.
Lawrence was tested for COVID-19 on Wednesday, and the school announced Thursday that he tested positive, meaning he must isolate for a minimum of 10 days, per ACC medical advisory group protocols.
As part of the return-to-play protocols, Lawrence has to pass a series of cardiac examinations, and Swinney said going through all the protocols would not allow him to be back in time for next Saturday.
ESPN's Andrea Adelson and The Associated Press contributed to this report.