You're looking at this left handed and upside down and inside out. (I am sorry to all you Southpaws.)
There are roughly 160 WR positions in the NFL. No one has deemed Kumerow worthy of a roster spot.
Currently Buffalo has 6 WR on the 53 and another on IR. They have had ample opportunity to bring him to to the regular roster and have not done so. The 4,5 and 6th WR are not world beaters. Gabriel Davis 15 receptions /205 yards/ 2 td, Isaiah McKenzie 14/113/1 and Andre Roberts 2/16/0. Roberts was a 3rd round pick a few years ago. But his on the bottom of their depth chart so he's not untouchable.
The question is why has no one selected him? The answer is, contrary to the opinion of fans, Jake isn't good enough. 2018 his PFF grade was 59. 2019 it was slightly better at 63.4 which means at best he's barely average. But that doesn't come from his receiving grade. In 2018 he caught 9 of 12 and in 2019 12/21. That's an average of only 62.5% boys and girls. His PFF grade more than likely comes from his blocking skills.
EQ has only caught 1 of 5 but the jury is still out on him. He will probably be given the rest of the year to get up to speed. Malik 4/5 so he catches the ball when it is thrown to him. He's not taking Lazard's place and that leaves MVS. 18/39 is pretty terrible but he has the speed that Jake doesn't have. Jake's 29 now so more than likely he is slowing down. If that's possible. I recall he wasn't very fast to begin with. MVS's 17.4 avg per catch is 2nd on the team to Lazard's 19.5. Among his duties MVS runs the go route. Jake won't be called to do that. That is also part of the reason for a lower reception average. He and Aaron have to be in sync for it to be successful. At times Aaron has overthrown and also under-thrown the ball. He did on the deep td pass to MVS. If you remember MVS had to slow down, almost stop completely and reach back for the ball just before crossing the goal line. If the defender had been there the ball would have been knocked down or intercepted.
In the past 10 years GB has had dozens of receivers the fans have begged to keep. Almost none of them amounted to anything after they were released. Not even as WR5 or WR6.
Aaron tossed Kumerow a complement but Aaron gives complements to the lesser players all the time. He didn't have a meltdown when Jake was released.
Time to move on guys.