A little history:
I started again a few weeks ago having had a pretty small backlog of items for upgrade fodder from before (maybe a dozen mythicals at most and 200 items or so). After some initial irritation that none of my items worked anymore, I started to really enjoy the game again. Whereas before, being a non-paying player, I had felt completely stuck as soon as I exhausted the strong items I could get from the campaign, now I could actually upgrade many of the epic items I found to legendary and mythical.
The new upgrade and matching system worked really well after I built a new mech. After upgrading a few items to legendary, I found that I could be competitive around rank 4, and then slowly but surely move up to rank 3 and then rank 2 after grinding the campaign enough to upgrade more of my items.
There were certainly plenty of arena matches where I'd think "how the hell is this person rank 3?", but that was overshadowed by the enjoyment of lots of close matches and the best part: beating much better mechs by exploiting a hole in the design.
After reaching the bottom of rank 1, however, the ratio of fun to sighing and quitting has changed for the worse. At least a third of the matches now are vs 2000 HP mechs with mostly mythical items. This wouldn't be a problem, except that the hope of closing this gap without pulling out a credit card is little to none.
To be clear, I'm not complaining that people have much stronger mechs than me -- I just think I've reached the point where the gap can't really be closed without paying, which seems to be the same point at which the game ceases to be fun.
The main culprit is this: many of the best items don't have epic versions; only legendary and mythical.
After exhausting all my easily accessible tokens, finishing the campaign (except Big Boy on insane) and grinding Big Boy a few hundred times, I have found 2 legendary items, neither of which are very useful. To compete with strong mechs, I need to find 3 legendary armor plates (I have 0) and a few of the strongest weapons. My rough guess is that I'd need to find about 100 more legendaries to achieve this, or 50x as many as I've found so far. This does not sound fun.
Anyway, a suggestion: give all items an epic version so non-paying players have a reasonable chance. Otherwise there is none.