I'm not going to claim to be an expert on whether or not this player will make it. I see what I see from stats and clips, and what I see is a player that has the physical tools to make it in the Prem but not necessarily the on-the-ball ability. He is sloppy on the ball. Whether or not that is something that Lampard is well-suited to cure, and what he looks like in a full ninety minutes in context, is for others that watch a lot more footy across leagues to evaluate IMO.
I will claim to be an expert on things like probabilities and risk management. Given what we're expending for a clear look, and the option to make a permanent move, this seems like a good deal. It doesn't cure our immediate problems. That also doesn't have to be the purpose of every move we make. If you're looking for this player to be the savior that keeps us up, you're probably going to be disappointed with the move. I don't think that's the role he's meant to fill.
That's strong - there are very few players (eg: young Ronaldo from United) that approach zero-risk - but it's the sort of low-risk, high-upside play that I would like to see us do a lot more of.