After a disappointing start the Warriors ended their European interest for the season with a 20-10 win over Wasps and a 23-16 win over Dragons at Rodney Parade.
Sean told the Evening Times: “The statistics show that this has been our most successful ever Heineken Cup group campaign so that is beyond argument.
“To post a 50% success rate from a group that included the current European champions in Toulouse and two-time winners in Wasps is really pleasing.
“On top of that we have done the double home and away over the Dragons who have long been one of our toughest rivals in the Magners League. So that is a great way to finish the European campaign.”
Sean added: “But I guess I am still nursing a sense of what might have been had we had all our big names fit for the start of the group stages.
“The game that killed us was the loss at Wasps back in October and for that one we were without Al Kellock, Johnnie Beattie and of course Chris Cusiter. I challenge any side not to struggle with those types of absences.
“But the big plus for me is the way the young lads have learned as they have gone from game to game. Guys like Ryan Wilson have come through and now they know they have what it takes.
“We can look back at this Heineken Cup campaign and hold our heads up high.”
Sean was keen to single out scrum-half Colin Gregor for his standout performance, saying: “Budgie was superb. He has come on leaps and bounds and I think the big thing for him is that he has, for the first time in his career, had a long and settled run at scrum-half.
“But DTH van der Merwe is just lethal right now. All in all I think we can look forward to the rest of the Magners League campaign with some optimism.”