Well that would be the case if I would be nearing deckout: but most of the times I simply HAVE to draw to get that next shield.
First, I have used this deck in the past with really good results (considering the upgrade count and ease of building the deck etc.) against FG's.
Second, as has been pointed out skip the FG's that are suggested as skips.
Lastly, I am taking you as correctly stating you are not over-drawing with the deck.
This all leads me to the conclusion the poor results are due to a small sample size (50 matches is less than 1 per FG!), starting your shield-chain too early, or being a victim of poor draws (happens to all of us time-to-time). Remember, if the opposing FG doesn't require starting the chain 'early' (has direct damage spells, small chance of momentum, etc.) then don't start the chain until you
HAVE to start it. This shrinks down how much shield-drawing you have to do and leaves you to draw only when you need pieces of the finishing-combo.