Stat inflation has caused a crisis in this game. We have lost a few key players in our syndicate because of frustration over it. They have watched new players and even mini players catch up to their stats in a few months what took years to build. God forbid I actually post something constructive in this forum since there are only trolls left but I thought I would give it a shot. Silly me.
These are not original ideas. Other GREE games use similar mechanics to augment against the downsides of being of high level.

The first (I’ll post more later) is to skew stats upwards with a percentage based investment leveling system. As a player levels they will receive 1 investment point per level and can invest it in a 5 prong investment ladder. A level 250 would have 250 investment points to invest in the ladder. Parts of the ladder could have level restrictions. Below is an example of such a ladder. The key is to give higher level players “breadth” in the their stat boosts and bonuses to offset the disadvantages of being of large level (mainly being a point target during wars). Stat inflation would still happen but it would benefit higher level players more than lower level players. There would be more horizontal competition and less vulnerability from lower level players. These bonuses would be stackable and there will be some variation based on player choice.

Armor Specialization (1-10%) -->Armor Expertise (1-20%) --> Armor Mastery (1-50%)--> Strongman (5x5% influence)
Vehicle Specialization (1-10%) -->Vehicle Expertise (1-20%) -->Vehicle Mastery (1-50%) --> Taskmaster (Energy regen 5x5%)
Explosive Specialization (1-10%) --> Explosive Specialization (1-20%) --> Explosive Mastery (1-50%) --> Shock and Awe (5x5% boss damage)
Melee Specialization (1-10%) --> Melee Specialization (1-20%) --> Melee Mastery (1-50%) -->Extortion (5x5% IPH)
Firearm Specialization (1-10%) --> Firearm Specialization (1-20%) --> Firearm Specialization (1-50%) --> Intimidation (5x5% building reduction time)

I would suggest putting a level cap on the last “tier” of bonuses to something like level 150. That would give vulnerable higher level players an extra edge in battle. For example a level 170 could afford 2 full bonus tiers, so during a syndicate war they could score higher (influence bonus) and more often (energy regen bonus) to offset the amount of point scored against them because of their high level. You could also give away prizes that add extra skill points to the mix (up to 5) so that at level 250 could afford 3 full tier bonuses. When you extend the level cap, you could add another layer of specialization with a cap to give those players ultra high level players another edge.
You could sell and give away (as prizes) tier reset kits. Gold players will buy these to optimize their experiences during different events. Intimidation + Extortion for LTB, Shock and Awe + Taskmaster for bosses, etc. Free players will have to make an investment choice that best suits their long term goals. Taskmaster will help gain stats through events, Strongman would have big consequences during wars. You could also invest your points widely and just go for extra stat points. This system will only work, however, if the bonuses are not calculated into the cost of events and remain real investment choices with real value.

The over arching issue with the stat inflation changes is that GREE does not value their players past investments. This needs to stop. GREE needs to inject back into the system real value for commodities, whether that is IPH, gold, respect, or simply player time investment.