As announced previously, after two years on a Ducati, Jorge Lorenzo will move to Honda for 2019. Prior to his time with Ducati, Lorenzo joined Yamaha in 2008, was second in the MotoGP point race in 2009, and took the title from teammate Valentino Rossi a year later. He was then world champion again in 2012 and ’15.
Switching brands has in general not been easy for riders. When Rossi, after two MotoGP championships on Hondas (2002, 2003) switched to Yamaha, the transition was a close-run affair but he managed to put the Yamaha on top in 2004. Yet when he went from Yamaha to Ducati for 2011 and ’12, he could not make the transition. Returning to Yamaha in 2013 he apparently needed time to assimilate techniques developed by others in his absence, climbing from fourth in the championship to second in 2014.
The nature of the problem became clearer when Lorenzo, too, went to Ducati in 2017. Lorenzo’s corner-speed style conflicted directly with the Ducati’s weakness in apex speed. Despite continuing effort by Lorenzo to adapt to the bike and Ducati’s work to adapt its machine to him, he did not win a race until this year, after which he declared he would be on a different bike in 2019. The problem is that both riders and bikes are specialized with respect to riding style, making it very difficult for a rider of one style to adapt to a machine evolved for another.
Source : https://www.cycleworld.com/corner-speed-vs-point-and-shoot-can-motogp-rider-change-his-style