Is OP statement what you consider 'evidence'? Yikes....
He merely made some statements, some of which were facts (Pet does indeed have CC) and others were just... opinion and/or false statements.
(The pet can CC but not neccessairly WILL counter CC if you CC).
All in all, this were not at ALL evidence, nor even a strong case for Summoner being OP.
Let me break it down for ya aye.
1) He did not have ANY numbers on ANYTHING that summoner has.
What <insert stat> does Summoner have? How does it compare to others? What's the damage, the range, the area and the cooldown of the abilities? This just the tip of the MASSIVE iceberg that has to be considered. This also has to be done to EVERY class, be compared, give as many possible (the more, the better) scenarios to determine which would come out on top. Since OP is a term relative to other. At this point, I'd be confident to say he did bring (some) evidence. Although a flawed one.
2) Now, even if he DID manage to state ALL of these things and did so correctly, that still is not evidence but rather a hypothesis. Although a crediable one with facts and numbers backed up behind it.
How does this fare in PRACTICE? Since it's almost impossible to cover every single action in every single situation, practice is a neccessity.
Now! If he have the numbers, the statistics, the meta has settled and they found NO weaknesses or NO strategies or builds to counter Summoners, and if Summoners were dominating in the top ranks - THEN we have a clear evidence.
And regarding practice; from what I have seen, Summoner is actually in the minority among the top ranks.
If I recall, they were second lowest (in number), behind Force Master. Although this does not indicate that they are the (second) weakest class, but could as a matter of fact simply be a case of an underrepresenting class. However, I think it's safe to say that Summoner is not 'OP'.
3) What defines OP? At what point do we call one OP? Let's say in a scenario where the meta has settled in the west (I REALLY doubt it has though) and tournaments or arena statistics were showing (among top level play) that Summoners were the dominating class. At what point are they OP? 60%? 70? 80? I believe it's natural for one class to fare slightly better than others, 60% win rate would be fine for me but perhaps not for you.
This thread is nothing more than a 'Summoner is OP' 'Summoner is not OP'. All believing they are right but none of them are giving ACTUAL evidence, number or statistic to back it up.
Also; Noone is giving an idea of how Summoners are supposed to be 'fixed' (if they indeed needs to be fixed).
I really don't see anything that remotely resembles a constructive critism about this class.
I am not saying this is right or wrong, just calling it as I see it.
Here is the rankings. Although I realise now that this is at level 50. So not really all that relevant.