I broke down your comment into 4 points to address everything, but I didnt change any text or anything:
Quoting: TJTwolf
(1) EJ,Timmins, Makar, Meloche is also probably ready for the big time, a guy who nobody mentions and is a better choice at 3rd line D, because that's generally your shut down pairing. He may not be the better player but is better suited to the role. Alt, who I admit is way below Deangelo but even so there is no fit there unless he's going to be a 6th, 7th, 8th D, which Alt is again a better fit.
(2) He's also another diminutive D. Stack the D with them and get hammered around the rink. I realise hockey is changing but you can't stock your team with guys who will consistently get knocked off the puck, teams will recognise it and play physical against you and wear you down, and to be fair whilst Girard, as an example, skates himself out of trouble a lot of the time, he (logically because of his size) doesn't win many physical battles.
(3) I agree with you about Timmins starting in the AHL but this is a terrible trade as when Timmins comes back there is no room for Deangelo unless one or the other is going to be a healthy scratch regularly. Sure EJ is going to be gone in a few years but how do you work it out now?
(4) Kreider as a UFA next year, for me is a no-no, and that's way too much of the future to give up.
(1) In terms of RHD, I think its foolish to assume that all of the Avs RHD prospects will become full time NHLers and turn down an upgrade just because it would require COL to keep Timmins in the AHL for a season. You cant assume Timmins & Meloche will become full time NHLers just like you cant assume Kaut will be one. If our RHD prospects become regular NHLers then thats great but we shouldnt bank on that happening. DeAngelo improves the team now and in the future (hes only 23).
(2) With this trade the Avs D for the 19-20 season would be: Girard, Zadorov, Cole, Makar, Johnson, DeAngelo, with one of Barberio/Graves/Connauton/Rosen/Byram/Timmins/etc filling in for Cole at the beginning of the season and for other injury replacements. Of these players, Zadorov, Cole, Johnson, Graves, and Connauton are all physical D men, with 3 of them (Zadorov, Johnson, Cole) being in the lineup reguarly. I admit I havent watched much of DeAngelo but based on his stats he doesnt seem to shy away from hitting, and neither does Makar. I wouldnt be worried about physicality at all with this D core.
(3) IMO Timmins should spend the year in the AHL, so we would roll with Makar, Johnson, and DeAngelo on the right side for this season. After another year of development, one of Timmins or Meloche would hopefully be ready to be a full time NHLer in the 20-21 season, and Ideally Johnson would be traded in the 2020 offseason (before the Seattle expansion draft). This would mean a future RHD core of Makar, DeAngelo, Timmins/Meloche.
(4) Purely from a value standpoint this trade is great. I mentioned in another comment Kreider could be flipped to another team to reacquire a 1st (or lower picks and/or prospects) since we already picked up a bunch of wingers this offseason. DeAngelo is worth more than Kaut and a 4th rounder in terms of value, so if we can recoup a 1st (or equivalent value) for Kreider then this trade is a win.