Features:

In general, this mod add base values of attributes to background icon tooltip and character hover tooltip. 
By 'base values' I mean the values that are not affected by things like traits, perks, equipment, injuries, which are the numbers you see when you 'click here to level up'.
See details in below:

1. Take a 'snapshot' of a brother's base attributes values when he first joined the company, then put it as an additional content after the original description, which displayed in the tooltip when you hover over the character background icon.
For each attribute, the first number is the value when he joined, and the number in round brackets is the value he can get when he reaches level 11 (if you choose to increase this attribute every time) .
And these numbers shouldn't be changed no matter how you actually choose when leveling up.
This feature should take effect for every brothers no matter how they joined the company(companions of the origin, hired from town square, meet along the road...).

2. Add base attributes values to the tooltip which shows when hover over a bro in roster.
For each attribute, before level 11, the first number is the current value, and the number in round brackets is the value he can get at level 11 if you always choose to increase this attribute from now on; At or above level 11, both numbers are the current value. 
Unlike in feature 1, these numbers may change.

3. When an event which changes the background description occurs, such as one background converted to another (cultist_origin_vs_uneducated_event.nut, cultist_vs_uneducated, flagellant_vs_monk), the new background story will be added before the old description in stead of override it. So the attributes values will be retained and you will always be able to know who the brother used to be.

Installation/Uninstallation:

Please back up your .sav files before using this mod.

Put the .zip in \Battle Brothers\data\ to install, don't unzip it. It can be used for old saves, but feature 1 will not take effect for brothers who have joined the team before installing this mod.

Delete the .zip file to uninstall, it shouldn't damage the saves that use this mod, but it is still a good idea to back up the .sav files.

Requires modding script hooks, works on game version 1.4.0.49.

Compatibility:
This mod modifies player.nut, tutorial_contract.nut and gladiators_scenario.nut via mod_hooks;
overrides xxx_intro_event files (the event that will be triggered when a campaign starts for each origin , which are not so ofenly used in mods, I think);
overrides the files that listed in feature 3. (If other mods you use also need to modify these files, you can enter the .zip and find them under \scripts\events\events, delete them to avoid conflicts. And feature 3 will no longer take effect.)

Credits:

This mod was inspired by the following mods and the main part comes from them, I simply did a some integration work:
Leonion's Smart Recruiter
Vazl's Veteran Attributes 11
zhy's The background permanently displays level 1 and level 11 attributes
Thanks for their excellent work!