Scott Servais

51-year-old Seattle Mariners manager Scott Servais made a bet with his star pitcher Edwin Diaz -- get 50 saves and I'll swap out my dad hair for your flashy designer fade. Diaz got the job done on Saturday -- so, Scott got the chop ... and it's all on video. Diaz and Servais made the bet way…

Here's Seattle Mariners manager Scott Servais making good on a challenge to his players ... and making a case for coolest MLB manager around. Servais told his guys that if they scored 10 or more runs against the Oakland A's he would reward them by sportin' a swagged out travel outfit -- complete…