Okay, great, let's look at your original statements.
So you claim his serve started booming a few months before the 1990 USO. Moreover, you claim that Sampras
clearly stated this. In fact, Sampras never makes a reference to such a specific time frame. He says very generally that he started serving aces in 1989 and that his serve kept improving throughout 1990. Please quote Sampras
clearly specifying a time frame beginning a few months before the 1990 USO.
And please don't play with his words. If he clearly makes a reference to a time frame of a few months, then all you should have to do is quote his clear statement specifying it.
"When Mats and I met in the second round [89 USO], it was my first appearance on the Louis Armstrong Stadium court at the original USTA National Tennis Center....I was a little apprehensive and still green--emotionally, mentally, and even technically. My forehand--my best shot-- was a little shaky, and in the big picture I had no backhand worth the name. But the one thing I suddenly did have was a serve. In 1989, I suddenly started serving up aces. Don't ask how, because I can't give you a good answer."
"I started my quest at Flushing Meadows [1990] as a dark horse, although I was definitely on the radar of my rivals, the pundits, and knowledgeable fans. Through 1990, I was slowly becoming a better mover and all-around athlete, and my serve--already vastly improved--just kept getting better. There was no magic bullet, coaching or techniquewise. Suddenly the big serve was just there, and getting bigger as the months passed."