User blog comment:Drago0661/Jack Bond - My Jackknife Deck/@comment-1755882-20140617140809/@comment-24232081-20140623010242

Thunder Knights, Drum Bunker Dragon has to add soul from the hand, meaning lossing card advantage, and with the limited number of targets you may not even have that luxury, making room in the deck. There won't be enough deckspace for 4 of both Thunder Knights, Halberd Dragon and Thunder Knights, Drum Bunker Dragon.

Also Thunder Knights, Drum Bunker Dragon only has 5000 power and 4000 defence, not very good stats when compared to Jackknife, that soulguard will be gone in no time. 5000 power doesn't hit very much either, so the penetrate won't bee seeing too much action, unless you use a link attack, but that uses up another possible attack, which is less than ideal. The move is very handy, but then Thunder Knights, Halberd Dragon just does the same thing but better due to his stats.

Therefore Thunder Knights, Drum Bunker Dragon, is not the best soulguard option.