Learn English – What does “run someone’s plate” means

look sense 12 - seem, appear to be, give the impression of being
to be up to [it, doing something] - to be able to do something (often, fit/healthy/strong enough)

The highlighted passage can thus be read as...

...they said I didn't seem to be sufficiently skilled (or fit) to play, so they dropped me from the side

The second citation just looks confusing because there are three different pronouns all refering to the same person (you when "they" are addressing the speaker, he when one of "them" is speaking to someone else, and I when the speaker refers to himself).

Showing something in its true light is largely similar to something showing its true colours. It does indeed means to show it as it truly is. It will usually be combined with show, depict, or similar, but because there is a choice of words there I would not say those words were part of the idiom.

As to your secondary question regarding as the year, that applies to 1992. 1992 was adopted as the year to show them in their true light. "The year to" do something, or indeed "the day to" do something, or "the place to" do it (etc. etc.) means the appropriate point in time, space (etc.) to do it. So these historians determined that 1992 was the right year to depict them in their true light.