Robinson left to rejoin 49ers Coach Dennis Erickson, for whom he served as assistant coach and defensive coordinator on previous staffs.
"Willy's contributions in his four years here have been invaluable," Cowher said through a press release. "Not only is Willy an excellent football coach, he is a quality person who not doubt will be missed. I could not wish him more success in his new position."
Said Robinson through the same press release: "I appreciate the opportunity Coach Cowher and the Rooney family presented me. Not only was it an opportunity that meant so much to my family and me, it also was the generosity, direction and sense of family that the Steelers organization has given me. Because of family situations, the Steelers organization allowed a window of opportunity for me to return closer to my home."
Robinson was interviewed by Cowher for the Steelers' vacant defensive coordinator position. Cowher must now fill both coordinator positions and name new coaches for wide receivers and defensive backs.
It's not known whether Cowher will name a new quarterbacks coach. The position was created for Tom Clements before the 2001 season, but he's left for Buffalo to serve as new Bills Coach Mike Mularkey's offensive coordinator. The announcement by Mularkey is expected to be made at 4 p.m.
Mularkey may also have an announcement concerning Dick LeBeau, who is considering offers from both the Bills and Steelers to become defensive coordinator.
The five players signed from the practice squad were OT Josh Burr, OT Morgan Pears, C Jimond Pugh, DE David Upchurch and FB J.T. Wall. Also signed were P Mike Barr, DB Nashville Dyer, OG Jim Jones, LS Chance Pears and WR Brian Robinson.
Dyer and Robinson signed with the Steelers last year as rookie free agents and were cut before camp.
Barr, Burr, Dyer, Pears and Robinson will be allocated to NFL Europe.
Clements, Robinson move on
Scout Football Top Stories
Biggest Midlands Risers in the Scout Top 300Taking a look at some of the highest movers from the Midlands region in the newly released Scout Top 300.
Scout Football11:08 AM
South: Movers in the Final 2017 Scout 300The final Scout 300 rankings are out and here are 10 moves you need to know about out of the South...
Scout Football10:39 AM
The Final Scout 300 for 2017Scout releases the Final Scout 300 for the Class of 2017 and Antioch (Calif.) running back Najee Harris ends the year as the No. 1 prospect in the country...
Scout Football10:30 AM
Big Ten Facebook Live & Recruiting NotebookSigning Day is under three weeks away and things are heating up in the Big Ten. See the latest with visits and more along with a Facebook live rundown of the latest happenings in…
Scout Football8:55 AM