Based on the events that happened, it is apparent that Oden overwhelmed Kaido and if not for Orochi’s deceptive tactics, it is likely that Kaido would have suffered more than just that wound. But unfortunately war involves more than singular battles with an outcome instead decided by the overall usage of the pieces available for use. Orochi, as cowardly as he may be, took of advantage of Oden’s heart and used the Mane Mane no Mi to mentally and emotionally distract Oden. That moment in which Oden turned his back on Kaido created a blind spot in which Kaido exploited to land the deciding blow. At the end of it all, Orochi knew Oden’s heart too well and took advantage of it to give Kaido the edge in that battle. The difference between the past and the current events is Orochi’s inability to even conceive what type of person Luffy is. And that is where Kaido and Orochi have overestimated themselves, thinking that they know Monkey D. Luffy.