Creating a power vacuum with a load of weapon caches left behind and hastily trained folk guarding them, does have a pretty predictable outcome.
http://www.nytimes.com/2012/06/21/world/middleeast/cia-said-...
A lot of these guys ended up in ISIS, it would be foolish to assume otherwise. If you view America's foreign policy aim as maintaining an unstable middle east, then it's not a slippery slope argument.