Underdog Best Ball Mania Bible: Roster Construction Guide

Apr 19, 2022
Underdog Best Ball Mania Bible: Roster Construction Guide

In the first exploration of Underdog Fantasy’s Best Ball Mania 1 and Best Ball Mania 2, 4for4’s Roster Construction Tool helped highlight how many players you should draft at each position. That laid the groundwork for how fantasy managers should be approaching Underdog drafts, but the tool is even more powerful and can offer guidance on how those allocation suggestions best fit together across all positions.

Understanding overall roster construction will further help best ball managers formulate their draft plan before getting a sense of how to deploy that plan, based on which position they are spending draft capital on, which will be covered in Part 3.

For the entirety of this series, the primary metric used to measure success will be playoff advance rate over expectation. Best Ball Mania 1 and Best Ball Mania 2 had different playoff advance rates and this metric normalizes for those changes. (See full explanation here)

Underdog Fantasy Resources: Get a Free 4for4 Pro Subscription | Half-PPR Rankings | Underdog ADP | Roster Construction Tool | Advance Rate Explorer |

Best Ball Mania Research: Positional Allocation Guide | Positional Draft Strategy | Anatomy of a Final-Round Roster | Stacking Strategy | Building a Unique Roster

Best Ball Mania leagues are half-PPR and start: QB, RB, RB, WR, WR, WR, TE, Flex (RB/WR/TE) with 18 total roster spots. There are no kickers or team defenses.

See all Underdog best ball rules here.

Roster Constructions Performing Over Expectation

Over the course of Best Ball Mania 1 and Best Ball Mania 2, there were only six roster constructions that offered advance rates at or above expectation in both tournaments.

Roster Construction Usage (% of Field) - 2020 Advance Rate Over Expectation - 2020 Usage (% of Field) - 2021 Advance Rate Over Expectation - 2021
2-5-8-3 9.3% +0.6% 8.5% +2.9%
2-6-7-3 10.2% +0.6% 3.9% +1.9%
2-4-9-3 1.5% +0.4% 4.2% +1.6%
3-5-7-3 11.3% +0.8% 8.5% +0.8%
2-5-9-2 6.6% +0.0% 15.8% +0.4%
2-6-8-2 13.0% +1.8% 8.8% +0.3%


  • Research on positional allocation highlighted the strength of 2-QB builds and that sentiment is reiterated here. Of the six roster constructions to return advance rates over expectation in both seasons, five used a 2-QB approach
  • While the 2021 field overreacted to the success of 4-RB builds in 2020, there was still evidence in Best Ball Mania 2 that drafting four running backs is a viable strategy. Of the 15 roster constructions used in at least 1% of lineups, 2-4-9-3 returned the fourth-highest advance rate.
  • The Best Ball Mania 2 crowd generally dismissed roster construction strategies that showed promising results in 2020, most notably with 2-6-7-3 builds. That construction dropped from the third-most utilized strategy in 2020 to 11th in 2021 despite advancing at an above-average rate. It advanced at the second-highest rate among builds used in at least 1% of lineups last year. 3-5-7-3 and 2-6-8-2 also dropped in usage rate but have advanced at an above-average rate in both tournaments.
  • Although 2-QB/3-TE builds are prevalent here, 2-QB/2-TE builds that advanced beyond the first round showed some of the highest third-round advance rates in Best Ball Mania 2.
  • A 2-5-9-2 roster construction took first place in Best Ball Mania 2.

Roster Constructions WIth Mixed Results

Of the 13 roster constructions to be used in at least 1% of lineups in both tournaments, three had mixed results between seasons.

Roster Construction Usage (% of Field) - 2020 Advance Rate Over Expectation - 2020 Usage (% of Field) - 2021 Advance Rate Over Expectation - 2021
3-6-6-3 7.5% -0.7% 4.5% +1.7%
2-7-7-2 6.3% -1.8% 2.7% +0.4%
3-6-7-2 9.7% +1.3% 5.9% -0.7%


  • These overly balanced builds fell out of favor in 2021, all dropping in usage rate by at least three percentage points, but two rose in value, advancing at an above-average rate.
  • Although these roster constructions are balanced in terms of the number of players at each position, the varying success rates across seasons may highlight their usefulness with extreme drafting strategies. A 3-6-6-3 build, for example, may fly in the face of positional allocation suggestions but could be optimal for a team that starts a draft with six wide receivers in the first six rounds; the 2-7-7-2 build might sprout from an aggressive Zero-RB draft.
  • This group of roster constructions serves as a reminder that one (or even two) years of data should not be taken as gospel and exact builds should be fluid within every draft. The 3-6-6-3 construction is unlikely to maintain its status as the build that offers the third-highest advance rate as it did in 2021, while seemingly underperforming roster constructions could end up being optimal.

Roster Constructions Performing Below Expectation

Roster Construction Usage (% of Field) - 2020 Advance Rate Over Expectation - 2020 Usage (% of Field) - 2021 Advance Rate Over Expectation - 2021
3-7-6-2 2.2% -2.7% 1.3% -0.5%
3-4-8-3 2.4% -0.2% 3.5% -0.8%
3-5-8-2 8.3% -0.1% 11.0% -1.0%
3-4-9-2 1.3% -3.9% 5.2% -3.0%


  • While the roster constructions that have performed over expectation were weighted heavily towards 2-QB builds, all four underperforming roster constructions were 3-QB allocations.
  • Even with 4-RB builds being all the rage after 2020, two seemingly reasonable 4-RB constructions performed below expectation in both seasons. Rather than writing off 4-RB builds, this may serve as an example of how to properly weight positional allocations—in other words, even if 4-RB builds were optimal in 2020, many of them were unable to overcome a 3-QB build.
  • The idea that roster constructions should be a function of each individual draft rather than a rigid plan heading into a draft is exemplified by the fact that 2020’s Best Ball champion won the tournament with a 3-4-9-2 build.

Fringe Roster Construction Strategies

Roster Construction Usage (% of Field) - 2020 Advance Rate Over Expectation - 2020 Usage (% of Field) - 2021 Advance Rate Over Expectation - 2021
2-5-7-4 0.3% -0.4% 0.3% +5.2%
2-6-6-4 0.2% -2.9% 0.2% +3.6%
3-5-6-4 0.4% -3.6% 0.4% +2.4%
2-7-6-3 2.1% -3.2% 0.7% +0.8%
2-8-6-2 1.1% -3.0% 0.4% -0.1%
2-4-10-2 0.9% +3.9% 6.1% -0.7%
2-4-8-4 0.1% +6.1% 0.2% -0.9%
2-3-10-3 0.1% +0.8% 0.2% -3.6%
2-3-11-2 0.1% +2.7% 0.3% -3.9%
3-3-10-2 0.0% -5.4% 0.3% -4.1%


  • Extreme positional allocations can be a great way to separate from the field but can have huge swings from one year to the next. These exaggerated positional allocations may lose some utility if they gain popularity with the field, as we saw with 4-RB builds between 2020 and 2021.
  • There is a trickle-down effect that impacts the viability of extreme positional strategies. As you will see in the positional draft strategy article, early-round tight end strategies struggled in Best Ball Mania 2, which boosted the viability of late-round 4-TE builds that offered high advanced rates in 2021.
  • Extracting specific builds can help highlight some underrated roster constructions, such as the 4-TE construction. In the positional allocation article, 4-TE showed little in terms of advance rate in 2021. The same can be said for 4-RB builds in 2020.

Applying Roster Construction Techniques to 2022 Drafts

  • One of the hidden edges in Underdog tournaments is in roster constructions. Builds that have shown promise haven’t necessarily been used most often. Meanwhile, a lot of the 2021 field overrated 4-RB builds without properly weighting the strength of 2-QB lineups.
  • With two years of data to reference, evidence suggests that the majority of your builds should most closely resemble the roster constructions highlighted in the first section of this study.
  • As we’ve seen with the two championship lineups, even constructions that underperform as a whole should be part of every drafter's portfolio.
  • Fringe or extreme roster constructions don’t have to be a huge part of your roster portfolio since they are so infrequently used but they can return some of the most impressive results.
  • The third article in this series will be the most applicable, tying together positional allocation and roster construction by exploring when to draft each position and which constructions work best based on draft capital.

1. In 2020, the top two teams in each 12-person group advanced to the second round of Best Ball Mania with additional “wild card” teams advancing in order to meet the total team requirement for the second round, resulting in 20.8% of the field advancing to Round 2. In 2021, only the top two teams in each 12-person group advanced to the second round, resulting in 16.7% of the field advancing to Round 2. All references to advance rate over expectation are based on these numbers. (Back to top)

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