Dave Stockton is considered one of the best putters ever. He is also one of our long time clients and friends. His recent article in Golf World about Spieth and McIllroy putting poorly is insightful and right on. He notes that when Rory struggles with his putting he gets more mechanical. In our experience most players that putt mechanically putt poorly. This is because they are operating with their Left Brain trying to control the stroke while putting. They are being too careful and focussing on the wrong things to putt well.
Putting has to be simple and Right Brain driven. Focus on rolling the ball and imagining the ball rolling along your line all the way into the hole. The stroke should just happen. Any focus on the stroke and trying to control it or guide it while putting will block your athletic abilities and ruin the stroke. It will also reduce your feel for the speed of the putt. You do not need perfect alignment or a perfect stroke to putt well. Stop carefully aiming the putter. Stop trying to be perfect. These are very Left Brained things.
I agree with Dave, these two players will shake this mini putting slump off and continue doing great things on the golf course.