The Celtics are on verge of making their first big splash of the offseason. League sources confirmed to MassLive Friday that Danilo Gallinari is set to sign with the Celtics once he clears waivers this week. Boston has the ability to offer Gallinari their taxpayer mid-level exception worth $6.5 million. A league source tell MassLive that Gallinari is expected to sign a two-year deal with a player option in year two. Adrian Wojnarowski of ESPN.com was first to report Gallinari’s commitment to Boston.