In the end, I think the teamfight hinged on 1) CST having a bad team comp for this fight, 2) Thresh/Kalista going in too quickly, and 3) Doublelift getting his Flame Chompers down and putting out lots of damage. The analyst desk blamed Cris for the loss. While he made some mistakes, I don't think they turned the results of the fight.
Let's jump into the setup:
CLG tries to bait Baron. They swept out the banana bush earlier, but Coast placed a ward in it. CLG did not realize this and sets up inside this bush. Doublelift moves up to the river bush.
CST sees this and runs in. Leblanc is lagging behind.
Take a moment to look at the team comps and items. CST has very little AOE damage. Kalista has a Runaan's Hurricane, but has no crit and is built more for sustained damage than burst. CLG is a bit tankier and Morgana has a Zhonya's Hourglass built.
Crucially, Irelia's Flash is down. Doublelift has both summoners.
Kalista ult is about to hit the 4 in the bush. In between the first two pictures, Irelia and Leblanc both used an auto-attack on the pink ward. While it looks like most of CST is grouped up, Thresh is far ahead of the rest and Irelia and Leblanc will arrive late to the fight.
Kalista ult hits 4. Morgana threw out a binding at the last moment, and it immediately hits Thresh. Jinx starts to move up the river out of the bush.
Jinx casts Flame Chompers and makes auto-attack #1 with the rockets. Reksai tunnels forward.
Thresh Flay hits 4. Jinx moves up the river away from Irelia.
Reksai Unburrow hits 4. Jinx makes autoattack #2 with rockets. Kalista makes autoattack #1.
Irelia makes a small movement mistake and moves north. This will cost him a bit of distance later.
The 4 members of CLG land and have their first chance to do stuff. The lack of AOE damage on CST is apparent in CLG's health bars. Link is the lowest at ~60% health.
Jinx’s Flame Chompers activate: Reksai and Thresh are rooted. Jinx uses her Super Mega Death Rocket, which will eventually hit 3. Leblanc begins her Distortion forward. Kalista makes autoattack #2. Irelia is not in range to jump to Jinx and doesn't have Flash up.
Just to confirm, I went into a game and checked the range of Bladesurge. It does not seem to be enough to reach where Doublelift was standing.
Leblanc distortion hits. It's the only relevant AOE damage ability on CST and chunks CLG (especially Link). Unfortunately, Leblanc immediately hits the third Flame Chomper and is rooted, meaning she can’t ult Distortion. Morgana uses Soul Shackles and activates Zhonya. Jarvan tosses his flag.
Kalista Rends after 2 autoattacks. Probably because of the lack of ult Distortion, it kills no one (Nidalee is really low) so it does not reset. Jinx makes autoattack #3 and kites upwards.
CLG begins their counter-wombo combo. Sion starts his ult. Jarvan has tossed his flag to the right and is casting Dragon Strike. Thresh and Reksai are knocked up. Cris is running after Doublelift but might be barely out of range.
Irelia starts turning towards Nidalee. Jarvan’s flag and drag and Sion’s ultimate have knocked up 3 – Leblanc goes from rooted to knocked up and is around 10% health.
Jinx makes autoattack #4 and Kalista makes auto-attack #3. Jarvan begins Cataclysm on Leblanc. Irelia begins Equilibrium Strike on Nidalee. Both will be lethal.
Nidalee has a chance to escape if it weren't for Irelia. Nidalee was not ignited (look at summoner spells). Reksai and Thresh were locked up, and Kalista was out of range.
Right afterwards, both midlaners are dead but the health bars for CST are much lower. Jinx’s next autoattack will kill both Reksai and Thresh. The rest is cleanup for CLG.
--------------------------------------------
What's the conclusion? CST couldn't stack their damage with their CC because they did not go in together. Thresh initiated about 1 second too early. CST's composition is based around bursting someone down with Irelia and Leblanc, followed up with sustained damage from Kalista. Neither Irelia nor Leblanc could get to the fight in time. Kalista, Thresh, and Reksai don't have burst AOE damage. Their CC did not hit Doublelift and let him deal his damage. When Leblanc did go in for the AOE damage, Doublelift's Flame Chompers hit him and prevented his ult Distortion.
CST as a team deserves blame for this lost teamfight, far more than Cris. Cris made 3 small mistakes:
1. The biggest is a slight move North during the fight. This costs him a bit of distance to Doublelift and puts Double out of Bladesurge range (Cris's Flash was down) until it doesn't matter. Even without this mistake, I'm pretty sure Double would have gotten off 80%+ (2 autos, ult, auto) of his contribution during the relevant portion of the fight before Cris could jump on him.
2. At the beginning of the fight, Kalista and Thresh were closest to CLG. Cris was 3rd closest, followed by Reksai and Leblanc. Right after Kalista begins the ult, Cris turns North to autoattack the pink ward in the bush. This leaves him grouped tightly with Reksai and Leblanc, but then Thresh and Reksai jumped in and Cris couldn't follow. I put this more on the team than on Cris.
3. He sent one Transcendent Blades toward the North.
None of these turned the fight. Let's say Cris went directly at Doublelift. I'm pretty sure he still wouldn't have blocked the ult rocket. Cris has to jump in with Q, which I'm pretty sure deals enough damage to Doublelift to break Bloodthirster shield (~200 hp?) so E doesn't stun. Doublelift flashes away and heals. Nothing changes.
MVP goes to Doublelift. His Flame Chompers caught Leblanc and prevented the ult W on 4.