We didn't throw away any part of that game specifically. That's just what's going to happen in lategame when only 2 people on your team can deal any real damage and they aren't very fed (AD Veigar is going to be terrible late game no matter what you do). Malphite top was also not the best choice - realo didn't misplay him or anything, he just can't keep Riven from farming.
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Black Turtle did a pretty good job.