Byrne justified Warren Gatland’s decision to stick with him by playing a starring role in the demolition of an Italian side that finished with the Six Nations wooden spoon for the eighth time in 11 seasons.
Just seven days earlier, the Lions full-back’s yellow card in Dublin saw Ireland score two tries when he was off the pitch, and Wales never recovered.
“I owed the coaches, the fans and the players,” admitted Byrne.
“I let myself down last week, but the coaches stuck by me and I wanted to put in a performance.
“I thought I did okay, and it was nice to come away smiling.
Patient Wales built on fly-half Stephen Jones’ four first-half penalties, scoring three tries in 17 minutes either side of the hour mark as centre James Hook claimed a double and wing Shane Williams collected his 51st Test touchdown.
It was a satisfying, rather than spectacular, way to end a tournament that produced two wins, three losses and an over-riding feeling of what might have been.
Italy, ravaged by injuries during the 48 hours before kick-off, lost centre Gonzalo Canale and scrum-half Pablo Canavosio inside the opening 26 minutes, but they stuck to their task, even if it was mostly a brave rearguard action.
Wales, with the gifted Hook gliding through ever-widening midfield gaps, looked a million dollars at times, and there was an 18-carat showing by Lions Test scrum-half Mike Phillips on his return from injury.
Once again though, Wales had to settle for fourth spot – the ninth time in Six Nations history when a top-three place has eluded them.
“We either seem to win a Grand Slam or finish fourth,” lamented Byrne.
“We’ve got to break that cycle, and we will need to start next season’s Six Nations with a bang.
“It has been frustrating all round, but it is nice to finish on a high and be positive going into the next game (against South Africa) in June.”
Wales scorers: Tries: Hook 2, S Williams. Cons: S Jones 3. Pens: S Jones 4.
WALES: Byrne; Prydie, Hook, J Roberts, S Williams; S Jones, M Phillips; Jenkins, M Rees, A Jones; B Davies, Charteris; Thomas, Warburton, R Jones.
Replacements: Gough for B Davies, 15; Shanklin for J Roberts, Bennett for M Rees, P James for A Jones, all 63; Delve for R Jones, 67; Bishop for S Jones, Peel for M Phillips, both 70.
Italy scorers: Tries: McLean. Cons: M Bergamasco. Pens: M Bergamasco.
ITALY: McLean; Robertson, Canale, Garcia, M Bergamasco, Gower; Canavosio, Perugini; Ghiraldini, Castrogiovanni, Geldenhuys; Bortolami, Sole; M Bergamasco, Zanni, Tebaldi.
Replacements: Pratichetti for Canale, 4; Tebaldi for Canavosio, 25; Vosawai for Sole, Aguero for Perugini, 55; Bocchino for Tebaldi, 63; Ongaro for Ghiraldini, 65; Bernabo for Bortolami, 73.
Referee: W Barnes (RFU).