Kirwan has three players in mind after being forced to release Retallick, who injured the anterior cruciate ligament in his right knee in training four weeks ago, for the season.
It is believed that one is William Lloyd, a 2.03m tall player from Auckland B, and that the other two are New Zealanders playing overseas. Kirwan said he hoped to make a decision by the end of the week, pending, presumably, the availability of the two Kiwis abroad who are likely to have the experience that the Blues require.
"We've taken Culum out of the squad and it was a really sad thing to do," Kirwan said. "He'll be a big loss for us. The hardest thing about Culum [going] is replacing him because he's a big, tall man and he's got a lot of experience so when you look around to replace that it's pretty difficult. We're taking a little bit of time with it and making sure we get those decisions right."
Retallick's absence, and the overseas moves last year of former All Blacks Ali Williams and Anthony Boric, means Tom Donnelly, the former Highlander and Crusader, will begin his first season at the Blues ranked as their No1 lock.
The only other specialist second rowers at the Blues are Liaki Moli and Patrick Tuipulotu. The latter, a New Zealand under-20s representative, turns 21 in a fortnight. All Black loose forward Steven Luatua is a possibility to play at lock, as is the returning Jerome Kaino, but Kirwan is unlikely to want to limit those players' impact with a role in the tight.
With prop Tony Woodcock and midfielder Ma'a Nonu returning from a season at the Highlanders, loose forwards in Luke Braid, Luatua and Kaino and several talented backs including Benji Marshall, Charles Piutau, Francis Saili and Frank Halai, lock is the one area of vulnerability for the Blues.
Donnelly, 32, a 15-test All Black who last wore the black jersey in 2010, is a seasoned campaigner but struggled for game time in his two seasons at the Crusaders behind Sam Whitelock and Luke Romano.
The Blues are into their second week of pre-season training for the year and the hard work has begun early for Charlie Faumuina, the All Blacks prop returning to his franchise in a bid to lose weight.
The New Zealand players' collective dictates the All Blacks are on leave for another fortnight, but having decided he is "probably a bit out of shape", Faumuina returned yesterday (Mon), deciding it's easier to train with his teammates than by himself.
Faumuina, who enjoyed a family holiday in Rarotonga during his break, is the first from the national team to return fulltime to the Blues, though Luatua, Halai, Saili and Piutau have put in appearances.
"What we want him to do is get the balance," Kirwan said of 27-year-old Faumuina. "He is one of the key guys in our organisation and we are really proud of what the All Blacks have done and we want them to have a rest. But sometimes it's easier to come in and do the fitness work."
Faumuina had one of his best seasons in 2013, playing 10 tests, including four starts, but the calf problems over the past two years which have ruled him out of the June series against Ireland and France mean he has to be extra careful at this time of year.
The Blues play the first of their three pre-season matches against the Hurricanes in Masterton on February 1. Their first competition game is against the Highlanders in Dunedin on February 22.
