I think you read the article wrong. Sony is stating that they detected a large number of sign in attempts, which many failed, but 93,000 succeeded. The attempts were made using the data (they assume) obtained from the prior hacks on the various Sony sites. This is not a new breach, but a follow through with the data from prior breaches, probably due to the affected users not updating their credentials from the prior hack.
On issue that JoachimSchipper points out [1] is that Sony probably isn't rate limiting, or throttling login attempts, which is a security issue, as it opens up the possibility of brute force attacks