Nottingham does suffer from a nasty quirk of city boundaries and statisitics when it comes to stats like this.
Some parts of it are certainly very grim and poor, as with any big city, but a lot of the nicer bits of the city aren’t actualy within the city council’s boundary. Places like West Bridgeford are certainly within “Nottingham”, but actually are the responsibility of the county council.
Contrast that with a city like Sheffield, which on the face it of seems a very similar place, but has just been voted the UKs happiest city. But the city of sheffield includes everything from large parts of the Peaks and posh suburbs like Dore and Whirlow, to some idylic villages to the north. The grim bits in the middle are also there, and they have guns and knives and poverty, just like Nottingham, but its not so obvious in the stats.