UCLA's Myles Jack slides out of Round 1, leaves Chicago

CHICAGO -- Myles Jack fell out of the first round of the 2016 NFL Draft in a stunning development that underscores the concern teams have about the health of his right knee.

It was expected that Jack would fall in the first round -- the former UCLA star acknowledged Wednesday that he would understand if teams passed on him due to the possibility of future surgery -- but his availability for the draft's second day (Rounds 2-3) defied even the most grim expectations.

Jack, invited to Chicago among 25 prospects with a strong chance to be chosen in the first round, left the Windy City Friday, according to NFL Media insider Ian Rapoport. It's not uncommon for players invited to Chicago to leave before the second round if they aren't chosen in the first round. New York Giants safety Landon Collins, for instance, was among those who did so a year ago.

Jack tore his meniscus at a Bruins practice in September. He withdrew from school to focus on rehabilitation and announced his intention to enter the draft as an underclassman. Six months later, however, he had missed the NFL Scouting Combine, had only limited participation in UCLA's pro day, and scrapped a plan to hold a personal pro day at which he was expected to run his first 40-yard dash for NFL scouts.

Following his medical recheck in Indianapolis on April 15, Rapoport reported NFL clubs had mixed opinions about Jack's knee. Subsequently, concerns about the possibility of a second surgery, later in his pro career, arose. It's that concern that has led some teams to believe that, while Jack will be ready to play in 2016, his career might be shortened.

So who might end Jack's draft agony? Teams with two of the first five picks in the second round have a need at linebacker, according to NFL Media analyst Lance Zierlein: the Cleveland Browns and Baltimore Ravens, neither of which addressed the position in Round 1. Zierlein projected Jack to the Jacksonville Jaguars at No. 38 in his mock draft for Rounds 2-3.

As he waits to be picked, Jack's thoughts shifted to a different sport. A video posted Friday to Jack's Twitter account shows him dunking a basketball.

No one can fault him if that's his way of blowing off some steam.

Follow Chase Goodbread on Twitter @ChaseGoodbread.