Welbeck and Lallana were free transfers so, although they'll command a fair chunk in pay (and, likely, signing-on fees), there wasn't the c£25m transfer fee to stump up.
I'm only guessing and may be completely wrong, but his age profile doesn't seem to really fit with how we've been recruiting...
He's 27 in a few months, and it may be as simple as that.
We don't tend to go for players of that age as there's very limited, if any, scope to polish them up and enhance their value.