No, Reform changing to Alliance was not a split. The issue since the creation of the Reform party is a split of the right-of-centre vote. If, for example a riding where the vote is typically 60% convervative and 40% liberal has both an Reform/Alliance candidate, a Tory, and a Liberal, the Liberal is bound to win because of the split when, for example, the 40% vote Liberal as usual, but the conservatives split, say 35% Tory, and 25% Reform/Alliance.
Because of that the Liberals win more seats in Parliament than usual and the Reform/Alliance and Conservatives both getting a small fraction of what they would get if they were the only conservative ticket. So when, if there were a single conservative party, the house would ordinarily be made up of a roughly 50/40 split of Liberals and Tories (swinging back and forth between the two) and the remainder going mostly to the Bloc and pittance to the NDP, we instead end up with the Liberals getting the vast majority of the House and the Bloc doing better than either convervative party (despite the fact they don't exist outside Québec) and winding up leading the Opposition.