POSTED ON BEHALF OF JEFF GREGG
Hey everyone!
My name is Jeff Gregg, and I am the Lead Designer on World of Tanks Valor.
Welcome to "Let's talk about tanks!" The goal is to highlight specific tanks, one at a time, and really dig down into what makes them tick, how they are being used, and how approaches may be taken to improve them if necessary.
As you read you will see a lot of charts and data. All of this data compares the tank to every other tank of its tier over a sixtyday period. All data is pulled from Random Battles only.
This article is focused on the feared tier X tank destroyer from the U.K.: the FV215b (183). Let's get started!
Battles and Popularity
This Tier X beast is awesome and incredibly popular. Sporting a devastating 183mm weapon, the FV215b (183) can send a LOT of pain downrange.
How popular is it? Over the 60 day period it has been near the top of the battle count for all tier 10 tanks (that outlier is the Object 279 Early. We can see that everyone tried out their new toy before that tank normalized with the other tier X tank usage). There are a lot of tankers playing with this!
So how is this tank doing with these players? Is it dominating? Is it suffering? According to the data, it is performing at a very solid 50% win/loss rate:
Let's take a deeper look at the win rate. An average of win/loss doesn't tell us as much as some may think. The first thing we should do is evaluate WHO is using this tank when it comes to skill.
Below we see a grey curve (representing the skill of ALL players) and a blue curve (representing the skill of the players using this tank). The higher the curve, the more players at that skill level are using the tank. We can see that most players are right in the middle / are usually successful at ~ 50% win/loss. The lower the skill and the higher the skill, the fewer the players.
Now we might ask: "there are players with a 100% win rate?!" or "there are players with 0% win rate?!" Those are likely players that played once in this tank and won or lost and then stopped. Super low occurrence outliers.
The skill distribution of the players in the game is almost completely aligned with the skill distribution of the players using this tank. It is attractive to all skill levels, from the lowerskilled players to the superprofessional tankers:
So now that we see that neither pros nor amateurs are influencing the tank more or less than any other tank, let's look at the tank's win/loss compared to skill. In the below picture we SHOULD see two lines, one that represents the entire population's win/loss and another that represents this tank's win/loss. We can't see two lines, because they are almost perfectly aligned. Meaning if a tanker (in general) wins 55% of the time, he or she will win 55% of the time in this tank. The tank itself is neither hurting the tanker's performance nor is it giving he or she an edge beyond their skill:
So where does that leave us? We now see that the tank wins about 1/2 of the battles it is used in. We also see that a tanker's effectiveness with the vehicle is the same as with any other vehicle; it neither gives an advantage or disadvantage above and beyond skill level.
Weapons
But let's keep looking, continuing with that awesome 183mm weapon. How often are players shooting? Here is the breakdown of the average and median shots per battle by shell type:

AP Mk. 1 (Standard round)
 Average Shots per battle: 4
 Median Shots per battle: 4
 % of Shots per battle: 25%

HE Mk. 1 (Standard round)
 Average Shots per battle: 1
 Median Shots per battle: 1
 % of Shots per battle: 6%

HESH Mk. 1 (Premium round)
 Average Shots per battle: 11
 Median Shots per battle: 11
 % of Shots per battle: 69%
The above is interesting (and atypical). The average % of premium shells fired per battle for tier X tanks is 18%. But here, for this tank specifically, we see that almost 70% of the shells fired are the premium rounds.
Let's take a look at some more shot analysis:
Accuracy (hovers around 68%, the low numbers in the graph below are for the tier X SPGs):
The number of shots that pen their target (very effective penetration here, roughly 64% of shots pen. Low numbers in the graph below are for the tier X SPGs):
Damage per shot that hits (about 787hp per hit, super high numbers in the graph below are the tier X SPGs):
Damage per shot that hits AND penetrates (about 853, super high numbers in the graph below are the tier X SPGs):
Damage per battle (about 2,000 per battle, cumulative damage for all attacks in a battle):
Based on the above it looks like we can start to consider the following:
 Statistically the tank is balanced. If you JUST look at the numbers and graphs, you could even argue the tank is perfectly balanced when considering JUST win/loss.
 We aren't just considering math or just considering win/loss.
 People are drawn to the premium shells for this tank & the huge explosion and penetration potential those shells allow for. Even though these shells cost 20 gold / 8,000 silver per shot, meaning people spend an average of 88,000 silver a match on ammo alone.
 The tank's damage output is near the top of the heap in tier X
Survival, etc.
Let's keep looking.
How often does this tank survive a match? Turns out the survival is near the middle of the tier X tanks. This tank survives about 32% of the time.
How long does the tank live for in a match? It's about 5min and 5s.
How far does this tank move? Not much (which makes sense for a heavy TD at the higher tiers). Only SPGs move less:
How much damage does it usually block? Not much at all. Seems that if an enemy acquires this tank it will probably do damage to it if it can take a shot and hit:
Summary
We have analyzed numerical data on this tank.
We see that players of all skill levels are attracted to this tank, use this tank frequently, and are willing to send expensive shells downrange to help propel their team to victory. Much more so than any other tank at this tier.
We see that it hits like a demon but that fact isn't allowing it to live longer, survive more often, or win more often.
Action Items
Based on this we plan on doing the following:
 Reduce the HESH damage from 1750 → 1450
 Reduce the HESH penetration from 270 → 240
 Reduce the HE damage from 1750 → 1450
 Increase the ammo count from 12 → 20
The above changes will also impact the FV4005 and will take place on June 2nd.
In order to measure the impact of these changes once they are committed, we need at least 5,000 battles in the tank(s) to have enough data. Once we have that amount of info, we will report back here on what the results were and (if necessary) what the next steps will be.
If you have feedback about this process or have further questions, reach out! Stay tuned here for results of the test and for what the next tank we focus on is.
See you on the battlefield!