Their European adventure also came to an end against Toulon at the semi-final stage as the reigning GUINNESS PRO12 champions endured a frustrating campaign.
But Cronin and Conan were consistently two positives and got their reward at the province's recent awards night - the former winning Players' Player of the Year while the latter picked up the Young Player of the Year gong.
Conan, 22, has made 16 GUINNESS PRO12 appearances this term with Cronin making 12 - but O'Connor is adamant the impact the pair have made can't be overstated.
"Both players have had excellent seasons for us," said the Australian.
"Their impact on the field is quite telling in terms of minutes played and their impact on the games that they featured in and I suppose the supporters can appreciate that.
"But for me it's what they do away from the paddock that people maybe don't see, which has left a lasting impression on everyone within the environment.
"You forget how young Jack is and that it's his first year out of the Academy. His maturity and his drive belies his 22 years.
"I suppose for Sean there is no greater honour than being recognised by your fellow players but knowing Sean he will already be looking at ways on improving and kicking on next season both for himself and for the group."
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Guinness PRO12 Leinster News
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