i believe he was made way too weak against uchihas...
first against itachi; oro was someone who was in the top ranks of konoha and researched a lot of jutsus, how could he not know about itachi and his sharingan's abilities?? and ways to fight against a sharingan user? even guy knows some tricks about it... and jiraiya who was supposed to be on par with oro (knowledge and power wise) was able to stand up against itachi (and kisame at the same time), but orochimaru just completely failed!!
then against sasuke; albeit he may have never crossed paths with itachi before and didn't imagine he was so powerful, but what can you say about sasuke on whom he watched closely for 3 years?? this time he shouldn't have fallen so easily in a genjutsu!! he was sick but a lot of other characters were shown being very powerful despite their age and/or diseases... he should have been able to demonstrate one last time the power level which he attained when he was playing with five-tailed naruto. talk about being dumped!!
