Well there actually are a few things to be considered.
What is pure strength i Guildball? Everything that helps you directly win the game. 2" Melee, Passive value, kick values, dodges, how much momentum someone can generate, are the results that generate momentum useful? Movement speed.
If we take the Union for example it is no wonder why the explode. They consist of almost nothing but Super Star Players that are good in almost every fashion that can be presented to someone. Decimate was already insane, and now Brewers have access to Vecimate, which is absolutely broken from the standpoint of the above mentioned things. Alloy. Bonkers. Insane. Absolutely broken. I have no idea why I would ever bring anyone else for both damage and Goalscoring.
What is passive value? Reanimate, Close Control, Sturdy, all those abilities that do something without controlling player input, or only minimal input. One of the reasons why I think that Corsair is just idiotically insane. He gives a team that already is strong in the offense additional passive value that they never should have gotten to begin with.
The problem I see with every model being released / added they fill gaps that never should have been filled. Hag makes Corsair a better version of Shark that does not die. I am pretty happy that at least A&G can't play for them anymore.
Now the problem here is the imbalance between considering the gaps. If we look at the Morticians, they got Pelage and Skulk. Now some people know since S3 hit I am not a big fan of the Morts anymore, but those two models added the passive value that I was talking about and the Morts were in dire need of, because everything just steamrolled them.
To get into more detail, just in case the Passive Value thing flies over someones head because I explained it badly, here are some models with Passive value.
Corsair, Sturdy, Close Control, 2" melee, Tough Hide, the combination of those abilities goes up exponentially in strength, not linear
Velocity, Hoist, Compound, lots of Reanimate, close control, high def, basically undying, and then there is Horrific Odour and Gluttonous Mass
Pelage, Ghast, Casket, slowing doen the enemy, locking places, inf sucker and even if killed net momentum loss compare to every other model.
To almost none of the above mentioned things you need to do something to trigger them. They are almost all triggered simply by the normal interaction models have with each other on the battlefield