They pretty much have to draft the Towson guy

It's right there in the script.

The Saints have expressed interest in Terrance West, and sent several scouts to his Pro Day. At 5-9, 225 pounds, the Towson running back is stocky and tough to bring down. He has experience catching the ball, however he isn't the shifty, speedy back that could slide into the void Sproles left.

Additionally, West's stock has been rising and he will likely go higher than the Saints would prefer, with four running backs on the roster.

I don't think the Saints are interested in replacing Sproles's role in the offense, exactly. They've given every indication... up to and including out and out stating.. that they're planning to gear the offense toward more of a power running attack this year.

This doesn't necessarily mean the offense will be any less creative, it just means it will be different and will require different players who do different things.  Here, for example, is an article about Robert Meachem's value as a blocker which might give you some small hint at what they're thinking about these days. Anyway, I don't expect they'll just run down to the pound and ask for another Sproles because they liked the one they had. 

But it does make sense that they'll go with more offense in the draft.  Of course, they don't have to do that but they have been doing most of the fancy free agency stuff on the defensive side of the ball so... analysis, right?

Speaking of which, here's some good stuff from Angry Who Dat articulating more or less the smart people's consensus that the Saints are managing this supposed "closing of the window" thing pretty well. If I had a criticism of this... which I don't, actually.. but if I did, it would be to say, yeah but basically they've upgraded the secondary while cutting loose veteran talent on offense.  That's still an incomplete. Obviously there's a plan but let's wait until they draft this Towson kid before we go busting up the windows and stuff.