Are you setting the hook and then dropping the rod forward afterwards? This is the most common error I see. It slacks the line and pops the hook out. Also, set your drag semi tight to set the hook without line spinning off. Thumbing to me on hook sets is just room for error. Try to keep most of the slack out of your drift but sometimes the way they hit you just have to set that hook putting your rod tip almost to the water or rocks, etc behind you to pick up the slack. Then reel down on him, without dropping the rod forward, to get the slack and either loosen the drag or start thumbing. But this is more for those stunned winter fish...summer run are a whole different ball game. A big summer run...keep your drag loose , set the hook hard and quick and then hold on and watch the show!