MCEM - I do agree that it deserves a lower multiple due to a couple of factors:
1. Much smaller than USCR and SUM
2. Single facility in Humboldt, KS
3. Lower liquidity than USCR and SUM, though that's offset a bit by the dividend
SUM has been very active in the industry consolidating smaller players, as has USCR. I can see MCEM being an eventual target amongst the consolidation.
Those factors are why I think 6x EBITDA is fair, versus +10x EBITDA for the likes of USCR, SUM, VMC, EXP, etc. It's a 40%+ discount relative to those companies that still offers a 50%+ return from current prices.