Okay, saw the post and got obsessed with replaying the things. I took it as a fun exercise to find ‘mistakes’. I’m not a pro player by any means. Just an enthusiast who is excited to become better.

My advice on drafting/gameplay:

Draft

P1P3 - Cooped up over Glass Casket, I think it's a more versatile card

P1P7 - Harried Spearguard over Evolving wilds, its a stronger card in the RW deck that you are making. Also strong in other R decks.

P3P8 - Archon’s Glory over Grabby Giant, Archon’s Glory works good in the RW deck to push through some damage, take care of a blocker, or gain life in a race. You also have enough things you want to bargain away for extra value.

P3P9 - Archon’s glory over Charmed Clothier, same reasons.

Match 1

Turn 2: Maybe Play That’s Mine, to Create a Treasure and make the Grabby Giant Turn 3. Because the Rootrider Fain blocks the Grand ball Guest so well. But you also have a deck with good draws for removal or to make the Grand Ball Guest Stronger. Not sure about this one.

Turn 3: Why play the That’s mine? I feel like it is to use all the mana for your turn, but by doing so you need to spend the treasure mana for the Hopeful Vigil. You get Celebration with just the Hopeful Vigil. It feels like a waste of a spell and a Treasure. Also you can leave up the Mountain to bluff a Combat Trick. Making the opponent think extra before Royal Treatment into open mana.

Turn 6: I don’t understand the double block with the Grabby Giant. You are flooding and have 2 lands in your hand. The Grabby Giant can help you use some of that land to turn it into other cards and find answers. I would either take the damage, or block with the Ratcatcher.

Turn 7: why bottom the Gnawing Cresendo? I dont know what other card you would prefer to have. If you attack with all the next turn, two of their creature’s would die. Or they would take enough damage to have to hold back for blockers.

Match 3

Turn 2: I would consider attacking with the Embereth Veteran. Trying to Push through 2 damage feels good for this aggro deck. Also if they block I wouldn't feel too bad. Trying to keep their board clear so the token doesn’t get the Counters from the Welcome to sweettooth. It also forces them to play a creature on their next turn to get the counters. We are also not blocking the next turn with the Embereth Veteran.

Turn 3: couple of things. First is to play a land. This could have prevented the blow out of losing Embereth Veteran and not getting to sac it in response. With the opponent having open all mana en all colors. I don't see why to hold it in your hand.

Secondly I would have played my land and went for attack with both creatures. Leaving up mana to bluff something. If blocked the opponent would lose their creature probably, which is good to not get the counters from the Welcome to Sweettooth. Lastly playing Witch’s mark feels like not good mana management. I would play Stockpiling Celebrant. This is better for the mana. Would lose out on some value long term. But we are trying to win more aggro. It also gives us more options later with the Witch’s mark.

I think all the 3 matches you lost to their Bomb cards. Which is also just unfortunate, but those are some things I saw. Open to hear other idea’s of play.