O'Regan, 24, was teammates with Jack Eichel and Evan Rodrigues at Boston University, where the trio skated as linemates during Eichel's Hobey Baker Award-winning season of 2014-15. He played four seasons with the Terriers, compiling 154 points.
O'Regan was the AHL's Rookie of the Year last season after scoring 58 points (23+35) in 63 games and has scored five points (1+4) in 22 career NHL games. He will report to Rochester initially, with an eye on joining the Sabres down the road.
"We are very impressed with his skill level, certainly his hockey sense," Botterill said. "You look at last year, the success he had at the American Hockey League, we think he's ready to make the jump here.
"We've tried to build Rochester up to have a winning environment down there. He'll certainly help them there down the run and we're hopeful that, once he gets into our organization and plays some games, he'll be in the mix for a call-up."
Botterill characterized the market as favoring players with term, thus the Sabres were unable to move any of their other impending unrestricted free agents. He had discussions with teams regarding longer-termed players as well, which he believed set the table for continued talks in the offseason.
His willingness to trade players with term stems from the same hard truth that convinced him to trade Kane rather than pursue an extension. The current mix of players, he said, has not worked
"I'm not putting the blame all on Evander Kane," he said. "There's a lot of blame to go around - coaching staff, management, players - we have to be better in certain situations. The bottom line is the mix that we have right now was not working, so we had to make adjustments.
"So yes, Evander Kane was [traded] because we were able to get some assets back that were very helpful for our organization. Throughout the summer here, spring and summer, we'll be making more adjustments to help our organization."