It doesn't make sense to have Tyrod as the back-up QB. The Ravens aren't a read-option team, and it's safe to say they will never be. Joe Flacco has a completely different skill-set than Tyrod Taylor and Tyrod's style of QB might work better in a place like Washington, Carolina,San Francisco, or Seattle who have guys that run 4.5 40's and are capable of taking off and running for a touchdown as well as throwing while scrambling (I know Flacco can throw while scrambling, and I'm fully aware of his ability to make plays with his legs, but he's never going to make the running plays that Newton,Griffin,Kaepernick,or Wilson do and avoid an entire defense en route to the endzone.)
Which is why the Ravens should try and convert Tyrod to a position where "The Human Highlight Reel" can make them Wide Receiver or Running Back. Yes, I know that Tyrod has more experience holding clipboards behind Flacco and we're making huge bets on Flacco playing 16+ games for a 7th season, but I've got two arguments why it doesn't matter if Tyrod or Wenning is QB.
1: It's a new scheme so Tyrod can't play the familiarity card with a new scheme and Wenning is more suited for it than Taylor.
2: If Joe Flacco goes down for an extended amount of time the Ravens are screwed, we're talking about Top-10 pick territory regardless of whether Tyrod or Keith is the back-up.
The Ravens should take a chance and see if they can't turn Tyrod into a WR or RB. What's the worst that can happen?