Sure he has a few La Liga and CL titles under his belt.
But there was a time when GB was considered to be the heir of the world's best player title. When he was considered to be better than Neymar. When he was hyped to the sun and back. When he was the best player in his league.
Since coming to Real Madrid, Bale has been overshadowed by Cristiano for the entire time. Worst of all he hasn't grown as a player. One would be tempted to believe had he stayed in England he would have been considered one of the world's best for many years now. The British press are great at hyping their product and a player like Bale would have been made out to be better than the likes of CR and Messi.
Now with Bale not being part of Real's plans and the Spanish side seeming like the best version of themselves ever, with the likes of Isco and Asensio being the future of the club, thing's don't look so good.
Bale leaving and going to either Manchester teams can instantly make them CL contenders. And he instantly puts himself back in the spotlight to be a future Balon winner and the world's best.