Delvin Granberg (the DBU player who was the MVP of our regional) was drafted in the 6th round by the Red Sox. He was a senior. He signed for $40K after a year in which he hit .443 with 13 HR and 26 SB. He is 6’2, 224 lbs.
I would argue it would be difficult to have a better senior season than that yet he had zero leverage.
If you are a junior and want a shot at the big leagues and to pocket a little money for your efforts you almost have to go if you are drafted.