What would cause this weird bearing wear?

Taper is measured. You get the crank to 70° temperature and get a micrometer. You measure each journal at a minimum of two points accross the width of each journal. (note rod throws have 2 journals per throw) Taper will show up if you measure properly and consistently. Or - bring the crank to the shop that turned it (may not be where you paid for it) and have them chuck it up and run an Arnold gage on it. That will definately find any surface issues.
If the original crank was only polished when the engine was rebuilt there's a very good chance the journals had a bundh of taper. Usually the wear leaves it "in spec" but having some, then it's polished which makes what's there worse.