Much has changed over the 10 years that I have been a member of FUMBBL, but for the purpose of this article, I’ve decided to focus on the biggest change: switching from LRB4 to CRP. I would like look at some of the mathematics behind some of the changes and briefly discuss how that has impacted the game.

Mutation Access

Allowing multiple races to take mutations on single rolls has drastically affected the team-building scheme but also effected how the developers adjusted some key mutation skills.

Claws

This has been well-discussed already but I will just add that reducing armour to a min of 7 has greatly helped low-armour teams; however, it would be nice if it were -2 to a min of 7 so that at least 10 AV players could have some benefit vs. Claws.

Tentacles

In CRP: Roll 2D6, adding strength differential, need a 6+ to escape.
In LRB4: Both coaches roll 1D6 add strength, need tie or better to escape.

Let’s focus on a strength differential of 2 (the most common case, e.g. ST 5 vs. ST 3). In CRP with a 2 ST differential, you need an 8+ to escape (42 %), with a 3 ST differential, you need a 9+ to escape (28 %).

Let’s compare these values to what was required in LRB4 with a 2 ST differential:
If Tent rolls 1, need 3+ (67 %). If Tent rolls 2, need 4+ (50 %). If Tent rolls 3, need 5+ (33 %). If Tent rolls 4, need 6 (17 %). Never successful if Tent rolls 5 or 6... Leading to an overall probability of escape of:
Prob(escape) = 1/6 * [0.67 + 0.5 + 0.33 + 0.17] = 28 %.

Therefore, in CRP as compared to LRB4, Tentacles effectively gives the escaping player +1 ST. This significantly reduces the effectiveness of Tentacles, which I suppose was needed because it is no longer a doubles-only skill. Coaches should bear in mind that Tentacles are not as effective as they once were.

Piling On

This has also been well-investigated so I will keep it brief. In LRB4, it allowed you to RR armour rolls only... In CRP you can RR armour or injury rolls.

LRB4 (Claw+MB+PO vs. 9 AV, always using PO) = 21 %
CRP (Claw+MB+PO vs. 9 AV, always using PO) = 27 %
Practical CRP (Claw+MB+PO vs. 9 AV, only RR stuns) = 21 %

It is interesting to note that if you use PO in a practical sense (i.e., you don’t PO vs. KO and you don’t PO when you haven’t broken armour), the probability of a casualty is comparable to LRB4; however, PO gives you the potential to RR armour or injury rolls for more ‘key’ players or situations which can increase your probability of a casualty by ~ 6 %.

Dauntless

In LRB4: Roll 2D6, if total > opp strength then Dauntless works.
In CRP: Roll 1D6 + player strength > opp strength then Dauntless works.

LRB4 (vs 4 ST) = 5+ = 83 %, LRB4 (vs 5 ST) = 6+ = 72 %, LRB4 (vs 6 ST) = 7+ = 58 %
CRP (2 ST vs 4 ST) = 3+ = 67 %, CRP (2 ST vs 5 ST) = 4+ = 50 %, CRP (2 ST vs 6 ST) = 5+ = 33 %
CRP (3 ST vs 4 ST) = 2+ = 83 %, CRP (3 ST vs 5 ST) = 3+ = 67 %, CRP (3 ST vs 6 ST) = 4+ = 50 %

Hence, CRP makes Dauntless less effective for low-strength players and slightly less effective for 3 strength players. In particular, 3 ST vs 4 ST in LRB4 and CRP are of equal probability but it is more difficult for 3 ST players to reach 5 or 6 ST players, which I feel is reasonable. As well, in LRB4 Dauntless required doubles whereas now in CRP it does not for most teams, hence reducing the effectiveness.

Dirty Player

This has also been well-discussed but reducing DP from “+1 to armour and +1 to injury” to “+1 to armour or +1 to injury”, as well as increasing the probability of being caught has greatly reduced the effectiveness and prevalence of dirty players.

LRB4: Without the Ref watching you: Roll D6, on a 6 = caught. With the Ref watching you: 4+ = caught. Could also argue the call and on a roll of a 6, the player remains in the game.
CRP: If you roll doubles on either armour or injury roll.

Prob(LRB4 caught, no eye, argue call) = 14 %
Prob(LRB4 caught, with eye, argue call) = 42 %
Prob(CRP caught, don’t break armour) = 16 %
Prob(CRP caught, break armour) = 33 %

Impact on Blood Bowl

In general, CRP made more skills readily available but also somewhat reduced their effectiveness to compensate. That being said, they also increased the effectiveness of some otherwise rarely used skills (e.g. Piling On) which as we all know has now turned it into a very well-used skill. The reduced effectiveness of DP and consistently high prevalence of being caught has changed fouling from being a widely-used strategy to being more tactical in nature. Overall, the CRP ruleset (e.g. reduced Claws, DP, and Journeymen) has made it a friendlier environment for low-armour teams as compared to LRB4, while the ability to easily amass Claws on mutation-enabled teams has drastically reduced the effectiveness of high armour bashy teams at high TV (e.g. Dwarf and Orc). Overall, as its name suggests, CRP has created an environment which is more competitive across the races than in LRB4, in my opinion; however, there are still many tweaks/adjustments that I feel are necessary to improve the competitive balance further.