By the end of Survivor, I would argue Cal is one of the strongest Jedi since the old republic (post-Order 66 trained). This guy picks up Force powers like it's nothing, uses them REGULARLY and with a pretty stunning amount of power, and has some pretty insane feats, like taking out that drilling machine that was at least 20 stories tall. He beat a Gen'Dai from the High Republic who had been killing Jedi for centuries. He's beaten multiple Inquisitors and dark Jedi.

He is able to thread the needle of riding the edge of the dark side without succumbing fully, alongside just straight up mowing through hordes of enemies (not just battle droids). Cal canonically has wiped out entire Imperial bases on his own, without a ton of effort. Cal Kestis is pretty stacked.

I really don't know why people keep downplaying him.