The main arguments about the power of the tranq gun are (according to the people that WANT me to play Val on their team):
-The tranq slows the monster enough in the dome so that the team can do sufficient damage to him in that one minute. Without the tranq, the monster can just run around uncontrolled and you will probably not even bring its armor down before the arena runs out.
-Kraken. Need I say more? the tranqs are an absolute MUST vs the kraken. If you don’t have Val, your trapper is forced to take Griffin in order for the team to have something VS a kraken.
-Tranqs slow the monster’s advance towards your teammates, thus reducing the damage they take.
-If the arena is on cooldown/trapper not in position to throw it, constant tranqs allow your team to catch the monster quicker. It also allows them to keep a constant vision over them.
-A slower monster is easier to hit with things like the Orbital Barrage. If the monster isn’t tranq’d, you will never be able to land a barrage.
Now bear in mind that these statements come from the people I often play with in a hunter team. They are 0% open to any other medic than Val because of these points.