So I've made threads about this in the past and each time I've learned something about making these suggestions for fixing Mercs work. I consulted users over the Discord and was advised to keep suggestions as simple and direct to the cause as possible, so that's what I'm going to do now. I have also consulted Mastermind players, also on the Discord, who share my concern with Mercs' poor performance since the day City of Villains launched with the Mastermind archetype. I'm going to keep things as simple as I can think of. I'm going to list each henchman, a list of proposed changes to its powers like patchnotes would be presented, and my reasoning for enacting the changes I propose to each henchman. I will then summarize my proposed changes, why they're beneficial, and why there should be minimal objection. All numbers provided will be at base level 1.
Burst: Increase damage to 9.9 (3 ticks of 3.3), fix activation time to 1.0 like Assault Rifle -> Burst is for players. Resulting damage per cast cycle will be 1.98, or very slightly behind Thugs' Pistols
Heavy Burst: Increase damage to 18 (6 ticks of 3), which will bring damage per cast cycle up to 1.69 or just slightly higher than Thugs' Dual Wield
Auto Fire: Fix activation time to 4s like Assault Rifle -> Full Auto for players and widen the cone angle to 20 degrees. That will slightly increase damage per cast cycle to 0.9, or slightly above Thugs' Dual Wield, and allow it to hit far more targets than the current 5 degree cone angle does.
Why?: This will bring Soldiers' damage output much closer to Thugs as a reference point, who are pretty close to other T1s in terms of damage while Soldiers' were far behind. So this just brings the T1 up to par with the rest.
Medic: Replace Frag Grenade with another support power handed out in a manner similar to Stimulant: choose either an absorb shield or a regeneration buff enhanceable with healing. This power should have a duration of 90s and a cooldown of 4s. Stimulant should also have a cooldown of 4s and a duration of 90s.
Why?: Medic having Frag Grenade is detrimental to its function and survivability, and the henchman could stand to have a stronger presence in improving Mercs' survivability as, indeed, is its function.
Burst & Heavy Burst: Enact the same damage and activation time changes that were done for Soldiers.
Snipe: Reduce cooldown to 6s and change activation time to 2.67s similar to Assault Rifle -> Sniper Rifle for players. This will increase damage per cast cycle to 2.01 from its current 0.88.
Web Grenade: Add 15 Toxic damage (5 ticks of 3 Toxic over 8.2s) and shorten the recharge to 8s. This means a damage per cast cycle of 1.52.
Flashbang Grenade: Cut recharge down to 45s, increase -To Hit and other debuff durations to 30s. Increase -To Hit debuff to -7.5%.
Tear Gas Grenade. Cut recharge down to 45s, change -Damage to -7.5% To Hit, and increase debuff duration to 30s.
Why?: Strongly enhanceable -To Hit which, along with their hard control, applied much more consistently. Debuffs for half a minute, crowd control for 6s, should make Spec Ops a decent debuffing henchman that provides much of Mercs' survivability by reducing the enemy's chance to hit for a decent window of time. They also lack severely compared to some other Tier 2 pets' damage, and that would be addressed with the changes to their attacks and web grenade.
Burst: Same thing done for Soldiers here.
Full Auto: Fix animation and activation time 4s like Assault Rifle -> Full Auto for players, and reduce recharge to 30s. This changes the damage per cast cycle from 0.39 to 0.76.
LRM Rocket: Simply reduce the recharge to 30s. This increases the damage per cast cycle to 0.67 from 0.09 (lol).
Why?: This should help the Commando's AoE damage to be decent.
Serum: Cut down the recharge to like 90s or something and remove the crash.
Why?: Well sure it's like putting a tier 9 super armor on your pet, but the problem here is that it only protects a portion of your damage output from getting snuffed out, whereas for other players it protects all their damage and that makes it a lot more meaningful. Here, it's just a waste as you make one pet harder to kill but then neuter its offense by taking away all its endurance for 20s, a painfully long time, only a minute later. I wouldn't use this power even if it were given to me for free as it is.
So why do all this? Why should no one object? I see Mercenaries was built to be a sort of utility set with decent damage like Necro was made to be, but it just doesn't perform this function with the source of its utility being on terribly long cooldowns that stops them from being present for a great majority of the time. They also suffer very low damage not just from their type being resisted, but because their damage output is just plain low. Increasing their damage values to approach other henchmen is the logical thing to do here, and fixing their activation times like has been done for players' AR is also needed to help them go through their abilities so they can have their effects out faster. They have almost no other defense outside of their Spec Ops' CC and debuffs. Imagine Bots without shields, or Thugs without Enforcers (and damage), or Necro without the Lich. That's what Mercs is like right now.
Here is data produced by Galaxy Brain testing all Mastermind pets, and only pets, on SO enhancements. Mercs are dead last in single target. It also needs to be noted that Bots in the Single Target category, though only appearing ahead of Mercs by 10 DPS, is likely further ahead than this graph shows, so Mercs are relatively further behind than that.