In most cases they weren't. The conclusion still stands, early-mid game zerg is a lot better off with banelings against giant marine balls. Here's the new data:
You'll notice this time around that unupgraded marines are infact bad against roaches. Once the terran has combat shield there's a clear break even point at 4 roaches. Once the terran has stim and shields it's at 2 roaches (an almost irrelevant statistic, it'll always be more marines and roaches by this time). So in the very early game roaches work ok, but once the mules finish a few cycles, you better have banelings or infestors. Another thing to note is that speed roaches don't fair much better at all.
Things I didn't test were burrow roaches and armor/damage upgrades so theory craft follows. Perfect burrow micro can completely break this graph in favor of roaches by hiding hurt roaches and avoiding the walk in to range which favors marines. 3/3 upgrades would also favor roaches because marines go from 5 damage per hit to 5 damage per hit (marine damage upgrade is perfectly negated by roach armor upgrade) while roaches go from 16 to 19 damage per hit against a 3/3 marine.
The replay with the testing: http://replayfu.com/r/GFVxVf