Much comparison has been made between Errol Spence (20-0, 17 KO), Pacquiao, and Amir Khan. For Spence has distinguished himself in being able to stop Algieri within five rounds. However, the difference between Algieri and Spence was the natural size advantage of Spence.
For Spence bullied Algieri with his physical strength and power – Algieri is a natural junior-welterweight. Pacquiao overwhelmed Algieri with his speed. Algieri and Khan were roughly the same size – Khan is still new to the welterweight division – and Algieri's game plan, per his trainer, was tailored to known vulnerabilities in Amir Khan, his lack of defense and punch resistance.
So, while Errol Spence may truly be able to defeat any of the top welterweights, his performance with Algieri is no indication because the top welterweights – Kell Brook, Keith Thurman, Danny Garcia – are generally natural welterweights with power.
In interviews, Spence suggested that he was not looking for a knockout, but his demeanor in the ring made it clear that he was going for it. This was most evident in round four when Spence accidentally hit Algieri below the belt with a left hand; it was obviously low, Algieri winced in pain and signaled to the referee that it was low; and Spence continued to pounce on Algieri while the referee was in the process of warning him to keep his hands up and Algieri had not yet recovered.
Bodywork was the focus of much of Spence's offense, beginning in round one where Spence caught Algieri with a right hook downstairs as Algieri was circling away from him. In round two, Algieri waited on Spence to throw his left hand so he could counter with his left hook. But Algieri's left hook was wide and he never circled away when using the left hook, thus become a stationary target. This was the first time Spence managed to hurt Algieri.
Algieri finished the third round getting beat up against the ropes, so Spence went after him aggressively in round four and scored a knockdown from a straight left hand within the first minute of the round. The aforementioned low blow occurred within the last thirty seconds.
Another left hand sent Algieri down twenty seconds into round five. Algieri appeared to have injured his ankle during the fall. Without good legs, Spence charged at Algieri and knocks him down again at about the 2:12 mark. The fight was then stopped without a count giving Spence the TKO.
In the post-fight interview, Spence iterated that he is the number one contender to Kell Brook and that is who he is seeking, as well as Danny Garcia and all belt holders.