Actually the reason why we probably win so many games with him there is the fact that he isn't playing centre half, rather than him being the new Maldini
That may be a factor, but if he was as weak a link at left-back as many people suggest I'm sure teams would have exploited it more, even at this level.
What he does do is give us far more physical presence at the back, especially at set-pieces.
It might be tough on Herd, but if I was Tilly I'd be planning on getting two new centre-backs this summer and keeping Barrett at left-back.