Cronin has impressed at hooker both in the blue of Leinster and the green of Ireland this season.
On international duty he has had to settle for an impact role off the bench but with Leinster Cronin has taken his opportunities well in the battle with Richardt Strauss for the number 2 jersey.
For Murphy, who lines up at openside flanker in this team, it has been a real breakthrough year that culminated in an Ireland debut after a number of man-of-the-match performances for Leinster.
And Ruddock joins him in the back row at blindside after the fellow youngster enjoyed a distinguished season that saw the 23-year-old captain the Ireland Wolfhounds and gain his second Ireland cap, four years after his debut.
Leinster's arch rivals Munster contribute two players, firstly Casey Laulala, the former All Black who has been a star in midfield for the men in red all season long.
And the outside centre is joined by provincial colleague and loosehead prop David Kilcoyne in the Dream Team, while Ulster also have two players who make the side.
In the back-line there will be few surprised to see Andrew Trimble get the nod on the left wing, the Ulsterman putting in some brilliant displays this year both for his province and Ireland.
In the pack Johan Muller skippers the side from the second-row, the World Cup winner has been an inspiration for the Ravenhill outfit in his final season before hanging up his boots.
The Ospreys are now out of the running for the play-offs but they too are well represented in this year's Dream Team.
The Ospreys have three players in Alun Wyn Jones who packs down at lock, flying Canadian Jeff Hassler whose seven tries earn him a spot on the right wing and out-half Dan Biggar who is the top points scorer in the league with 204 points - no other player has broken the 200-point barrier.
The Scarlets look to have secured sixth spot in the table and they too have three players in the side, Gareth Davies getting the nod at scrum half after a blistering season that sees him top the league try-scoring charts with nine to his name.
At full-back Liam Williams is selected for an impressive season for both region and country, while youngster Samson Lee comes in at tighthead prop to complete the Scarlets representatives.
The Cardiff Blues also have a player to make the Dream Team in the form of Robin Copeland, the Irish number 8 has been an ever-present in the league this season - his last with the region before moving to Munster in the summer.
Glasgow Warriors have the final player in the team as Alex Dunbar who has impressed despite an injury-hit campaign. He joins Laulala in midfield.
The Dream Team was selected by a media panel made up of rugby writers - three Irish, three Welsh, two Scottish and one.
The RaboDirect PRO12 Awards ceremony will take place in Edinburgh next Sunday (May 11).
2013/14 RABODIRECT PRO12 DREAM TEAM:
15 - Liam Williams (Scarlets)
14 - Jeff Hassler (Ospreys)
13 - Casey Laulala (Munster)
12 - Alex Dunbar (Glasgow Warriors)
11 - Andrew Trimble (Ulster)
10 - Dan Biggar (Ospreys)
9 - Gareth Davies (Scarlets)
1 - David Kilcoyne (Munster)
2 - Sean Cronin (Leinster)
3 - Samson Lee (Scarlets)
4 - Johann Muller (Ulster) (capt)
5 - Alun Wyn Jones (Ospreys)
6 - Rhys Ruddock (Leinster)
7 - Jordi Murphy (Leinster)
8 - Robin Copeland (Cardiff Blues)
Related Links -
Provincial Trio Make PRO12 Dream Team
Tuohy Takes Spot In League Dream Team Line-Up