T.ruficollis or T.naumanni?

This morning I went to Beppu Koen to check if there's anything new and found this thrush among a large group of Dusky.I don't know why there were so many Dusky Thrush today, more than usual. I think there were about 30-40 birds flying, sunbathing, drinking, jumping all over the park. There's one fruiting tree which all these thrushes liked to visit and it was very exciting when they all went feeding frenzy, like all the birds flew up at once and in close range, gave me a bit of goosebump. I wish I were skillfull enough to capture those moments. Anyway, the point about this entry is I am not really sure about what this bird should be. See the one with reddish breast and plain greyish upperparts.

It has faint but notable rufous breast and a small part around malar stripes,
but not in any shape of streak or scale and does not extend to its flank and belly.

This is the only flight shot I got; note rufous tail and underwing coverts,
but no rufous on flank, belly and undertail coverts.

I followed the bird to its perch on a high dead tree. Though the bird appears to have distinct greyish streaking on its underparts when it was drinking water, its underparts actually look whitish from this angle. I notice that it has no rufous on undertail coverts and flanks at all, which led me to think that it's more of a T.ruficollis or Red-throated Thrush (or Dark-throated Thrush T.r.ruficollis) than a Naumann's Thrush (T.naumanni or Dusky Thrush T.n.naumanni). However, it also doesn't look exactly like the Red-throated Thrush and I later found at least 1 or 2 Naumann's Thrushes along with the flock of Dusky. The bird later flew out of the tree before I could get any more shots and flew out of the park area to somewhere afar.