It detracts hugely from your original point. If your original point was x, it would be the equivalent of putting -x next to it.
If he'd scored 10 goals so far the entire internet would have crashed under the weight of our lunatic fringe twitterati goading kopites and happy hammers about how we'd secured the world's greatest ever striker for a pittance. His price would be used as a badge of honour, like it is for Coleman. Everybody loves a bargain. The issue is simply that Sandro looks highly unlikely to get remotely close to Lukaku's tally last year. There's no shame in that, and it doesn't make him a bad player, but it explains why people are saying we didn't replace Lukaku.