This is according to BT sports expert Colin Edwards, who believes that the Yamaha M1 is almost the right one.
The doctor had covered the years yesterday and finished second in Austin.
It was widely expected that Marc Marquez triumphed on one of his favorite titles.
However, the Catalan sensation threw away the victory after he crashed on lap 12.
After the race, Rossi spoke in defeat, praising Rin's performance.
"It's not a shock, because Rins has been very strong since the second half of last year," said Rossi.
"He's always very fast, I made two braking mistakes, if not, maybe I can try an attack on the last lap.
"But it's true, he was a bit stronger, so I'm sorry I can not win for a long time.
"But on the other hand, we're good, we're fast and we do not give up, we'll try it next time."