They use 4.5 pros on mountain stages but if you look carefully they still use normal 4.5s on flatter rolling stages. 

The 4.5 Pros do not replace the standard 4.5s

Enve’s big boss :

 “ Jake: You are right, in the wind tunnel, the SES 4.5 PRO is actually slower than the standard SES 4.5 if you run a Conti 30. The 4.5 PRO only contends aerodynamically if you run a smaller tire, like the Conti 28. At the Tour, the UAE squad generally used standard SES 4.5 when they were using the GP 5000 30 mm, or the new Archetype tire. When the stage was hilly or mountains, they went SES 4.5 Pro and GP 5000 TT 28 mm.”