Apple has in-house lawyers, yes, but they were not the attorneys who tried this case. This case is way, way waaaaay too big for in-house counsel.
Apple was represented by Morrison & Forester (which, for reasons I don't understand, prefers to go by MoFo so you'll think they're cool) and WilmerHale (the big firm from the A Civil Action book and film). Samsung actually had the better counsel, at least in theory--Quinn Emanuel.
The reality is, in a case like this, Samsung was a huge underdog just on the fact that it was a US company versus a foreign one. America's patent history is primarily one of ****ing over foreign firms who presented legitimate claims in favor of rewarding and protecting American companies. The speed of the verdict, given the complexity of the issues, plainly demonstrates that the jury didn't really care what they were doing. They just wanted Apple to win.