Yeah, OG and Siakam screwed up a switch, Siakam ended up closing out way too late on Ellington while OG should have switched onto Olynyk (well, technically I think OG was supposed to stay on Ellington, but once Siakam committed OG had to find Siakam's man) but rotated up to a shooter at the top of the arc instead - at the same time Norm recovered to the same shooter (Norm should probably also have read that OG was not in the paint and rotated there instead, but the guilt order still goes Pascal-OG-Norm). OG finally realizes he needs to be in the paint just in time for Siakam to get blown by in an embarrassing display, letting Ellington get to the rim before OG can meet him with a good contest.
To top it all off, if Siakam just grabbed Ellington, wrapped him up as he blew by, it would be side-out again as the Raps had a foul to give. Instead, Pascal weakly swings at the ball (probably fouling him but not enough to get a whistle, not the way that game was called) and its a layup. Just a comedy of errors on that last play.
I was expecting to see BeBe back in the game to protect the rim, and the Raps to err on the side of giving up a rushed jumper if need be. Weird defensive play call, to rely on really young defenders to be able to communicate live switches (different from the MIL game where they clearly knew the exact switches to make, and didn't have to react on the fly).
It baffles me how the coaching staff didn't put an emphasis on fouling if you get blown by. And you're right, it didn't help that we have young guys on the floor covering the switches. I always thought we have poor end of game plays both offensively and defensively.