Gresh, who joined the station in a full-time capacity Jan. 7, will slip into the role Tanguay held since the station’s mid-August debut alongside Scott Zolak, an industry source confirmed last night.

Indications are that Tanguay, who holds a prominent television role at Comcast SportsNet New England as the anchor of the pre- and postgame Celtics programming as well as co-hosting on “Mohegan Sun Sports Tonight,’’ did not know the change was coming. He made no mention of a possible departure on yesterday’s show.

Neither Tanguay nor program director Mike Thomas responded to messages seeking comment.

The news of Tanguay’s departure comes just a day after The Sports Hub signed Fred Toettcher and Rich Shertenlieb, co-hosts of the morning “Toucher and Rich’’ show, to multiyear extensions.

It is uncertain whether Tanguay’s departure will affect pre- and postgame programming for Patriots games, of which the Sports Hub is the flagship station. Tanguay has hosted since July 2004, with Zolak and Gresh serving as co-hosts the past two seasons.

This isn’t the first time the acerbic Gresh has been paired with Zolak, a former Patriots quarterback. The duo co-hosted “The Gresh and Zo Show’’ on The Score in Providence for three years before the station changed formats in March 2008.

While The Sports Hub has held its own in the Arbitron ratings, particularly in the male 18-49 and 25-54 demographics, the “Tanguay and Zo’’ show struggled in comparison with the station’s 6-10 a.m. “Toucher and Rich’’ show and the 2-6 p.m. “Felger and Massarotti’’ show.

Before joining The Sports Hub, Gresh worked in an on-air role on Sirius satellite radio. The former University of Rhode Island offensive lineman has also hosted programming for ESPN Radio and appears regularly on Comcast SportsNet New England.

Tanguay’s departure became public via a Twitter message at approximately 5 p.m. from an on-air staffer at The Sports Hub, who wrote: “Gary Tanguay is no longer co-hosting the midday show at the Sports Hub. Gresh will take his place.’’ She later added: “#Devastated.’’

Both tweets were deleted less than an hour later.