ST. LOUIS — Tiger Woods and Phil Mickelson used to be seen as flip sides of the same generation. Woods was a two-seat Lamborghini, built for performance. He stood out from the crowd and left little room for others. Mickelson was a Subaru S.U.V., built for crowds. He was bulky and could accommodate everybody.
But those earlier versions, of Woods and Mickelson in their 20s and 30s, have given way in middle age to models that are more similar than not. Mickelson, 48, has turned himself into a sleeker machine who nosed out a player nearly half his age, Justin Thomas, the defending champion of the P.