Carlos Sainz saw perhaps his final chance of a front-running Formula 1 seat disappear this week. Red Bull have opted to extend the contract of Sergio Perez rather than bring him back. Sainz started his F1 career at junior team Toro Rosso in 2015, alongside Max Verstappen. However, Christian Horner and co. were wary of reigniting the tension between the two drivers. There was apparently a reluctance to reunite their two fathers, Carlos Sr and Jos, because they were the source of the acrimony last time. By keeping Perez, Red Bull believe they will maintain harmony. In theory, Sainz could still j…