Absolutely this.
People are acting like getting Thomas was an easy thing to do, because they only see he went just 5 picks ahead of our original pick.
It wasn't that easy. Maybe Beane tried hard but it was impossible. We didn't have 3rd round pick and it wouldn't be enough anyway. 2nd round could get us to 19 maybe, but who was the trade partner? Like you said, Eagles wanted Mitchell and would miss out if trading with us, Dolphins probably wouldn't trade with us at all, Steelers needed an OT and there was quite a run on them. 19th pick were Rams and they drafted Verse.
It is fairly possible that we had precisely zero chance to draft Thomas, but people will still act like Beane was an idiot who only cared about recouping 3rd round pick.