I feel we're moving in the right direction. That's the most important thing. The Big East has never had a coach change jobs within the league. Mike Tranghese, the Big East's commissioner, said the league has no rules against such a move but admitted he couldn't recall another school even interviewing an opposing coach. He also noted that that has happened several times in other conferences, including Jim Baron moving in the Atlantic 10 from St. Bonaventure to Rhode Island.
Schools are free to hire each other's faculty members as well.
Kentucky hired Tubby Smith away from Georgia. There's a whole series of instances across the country. In a year of relatively unattractive mid-major coaches ready to jump up a level, a young coach like Welsh stands out. In his six years as a head coach, his teams have played in two NCAA tourneys and three NIT's. PC also pays its coach near the bottom half of the Big East, so Welsh is seen as vulnerable by other schools.