Sure, watching a 10' noodle rod double completely over as a steelhead massacres you're favorite Hot Shot is exhilirating, but how do you feel when you watch that rod pop right back up and start wiggling again?  Doesn't feel real good, does it!

Having too much rod angle while plugging decreases your fish hooking
ability by:
-Decreasing the plugs ability to dive
-Giving the fish more time to spit out your plug
-Not allowing the drag to hook the fish

Having the plug rod pointing nearly straight up in the air creates lift on the plug itself and decreases it's diving ability.  Lower the rod angle as seen in the diagram and the plug will dive to it's designed depth, getting you where you need to be.

When a steelhead or salmon hits a plug we want them to essentially hook themselves, or at least have the point of the hook penetrate enough to make shaking it difficult.  To help this along we want to decrease the time between the strike and tension being relayed to the point of the hook.  With too much horizontal or vertical angle the fish can take the rod down a great deal farther before any tension is relayed to the point of the hook, thus giving it more time to spit the hook. 

If this is the case then why don't we just point the rod directly at the plugs?  In order for the plugs to run properly they need to be cushioned by the tip of the rod, so we still need to maintain enough angle to accomplish this.  In addition, the plug rod needs just enough angle to telegraph the strike back to us so we can spill coffee all over ourselves and drop that powdered doughnut overboard when the rod buckles over.

Here's some other points to remember:
-Use a 7 1/2' to 8 1/2' rod with plenty of backbone and a soft tip. 
-Set drags just heavy enough to point the hook into the fishes mouth while
still allowing them to turn and take line.
-Wait until the plug rod is completely buried before setting the hook.  If the
rod is bouncing the fish hasn't turned away from the boat yet!