The two best roster-managing clubs in the NRL showed again in 2019 how a long-term plan can generate success while others proved it's not as simple as retention equals success.

Success from stability

NRL.com Stats has crunched the numbers and found a strong correlation between the percentage of 2017 players retained and games won in 2019, with only the Cowboys bucking the trend.

No club had more of its 2017 squad still on the books in 2019 than Melbourne, with almost 59% retention over that two-year period helping them to 20 wins and a minor premiership.

Three other clubs with some of the highest retention rates joined Melbourne in finishing top-four on the ladder: the Roosters (second) had almost 52% retention, the Rabbitohs (third) around 48% and the Raiders (fourth) had 50%.

There is no question the Storm and Roosters have been the best clubs in terms of list management and investing in the right players over recent years.

Both squads have been bolstered by a huge proportion of players who have come through the junior system at each club.

Of the Roosters' top 30 this year, 22 played junior football at the Tricolours, while 21 of the 29 players to feature for the Storm in 2019 debuted at the club.

The trick there, of course, is identifying, recruiting and nurturing the right talent at a young age and being selective with which marquee recruits you are prepared to pay top dollar for.

The three clubs to significantly outperform pre-season expectations were Canberra, Parramatta and Manly with the latter two occupying the last two spots on the ladder in 2018 before finishing fifth and sixth respectively in 2019.

Roster continuity arguably had plenty to do with that.

Parramatta (48%) and Manly (43%) got rewards for persisting with players even though 2018 results suggested each may have needed a roster cleanout.

The Bulldogs finished 2019 strongly with a new-look squad. ©Gregg Porteous/NRL Photos

Upheaval leads to disruption

The lowest retention rates of any club were seen at Canterbury and Brisbane (both 32%) and it appears to be no coincidence both clubs were much better in the final third of the season once their overhauled squads started to click.

While Brisbane eventually snuck into eighth place there's no doubt it was still a disappointing season at Red Hill (particularly given the manner of their week one finals exit) while Canterbury were running last mid-year before hitting some form and finishing 12th.

The Knights had the third-lowest retention rate (33%) and had a tumultuous season in which a mid-year winning run was overshadowed by an awful start and arguably worse finish that resulted in coach Nathan Brown parting ways with the club.

There were three more clubs around 35%, including the bottom-two finishing clubs in the Titans (34.5%) and Dragons (37%) while Penrith (35.5%) had a season that mirrored Newcastle's in some ways with a horror start, mid-year run raising hopes of a finals berth before another slump.

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The Sharks, Dragons, Wests Tigers and Warriors were all in the lower half of the field for retention rates between 34% and 40% with only the Sharks scraping into the playoffs of those four.

Most of those – and particularly the Dragons, though they also had a lot of disruption as well – underperformed relative to their roster strength. A lack of continuity in key positions was arguably a factor in each case.

The odd one out

Even more so than Brisbane scraping into eighth with the lowest retention rate, the biggest outlier along the retention/success scale among all clubs was North Queensland, who had the second-highest retention rate at 56.7%.

In hindsight, a failure to refresh their roster in the time since their 2015 premiership win has hindered them over the past two seasons.

Father time seemed to catch up with some of those premiership heroes like Matt Scott, Justin O'Neill, Jake Granville, Scott Bolton and arguably Gavin Cooper, with a horror injury toll elsewhere in the squad proving a huge burden.

Whether the long-term deal to Kangaroos and Maroons star Val Holmes can help turn the tide remains to be seen.