I just thought I would run some numbers from our 2016 league. The #5 slot for each category is as follows:

Batting:Runs=943; Rbis=919; SBs=118; Ob%=.344; Slug=.458
Pitching: Ks=1562; Ws=102; ERA=3.6; WHIP=1.21

With 12 offensive players if you wanted a team that would finish in the top five each player would have the following number:

78.5 runs; 76.5 Rbis; 9.8 SBs; .344 ob%; .458%

With a 260 dollar budget and let's say the last six players cost $10 total, each of your remaining players cost $12.5. But offense gets somewhere from 60% to 70% so each offensive player would cost 12.5 if you stick to 60% or $14.58 if you go to 70%.
As for trying to figure how players relate to that average figure I don't think you are going to be crazy wrong if you figure 20 runs and Rbis for one standard deviation, 10 steals, and .03 for both on-base and slugging. Obviously, if you want to be getting players that get you into the top five you would like players that cost $15 to be doing at least as good as that top five player mentioned above. You might be getting guys that cost only $6 and don't have quite those numbers but balance that out with guys who are significantly better than that average elite player and of course it is tough to get those numbers at 2b, SS and c. I just think it is good to know where you need to wind up with, however you get there. Obviously you can go through and calculate the numbers for say the top 200 players or whatever, get the mean, get the standard deviation and convert that to a salary. This is kind of a simple analysis for lazy people (like me).

For pitching, let me list some pitching results:

Starting pitchers:

11>200ks; 3>190; 7>180; 7>170; 14>160
2>20 w; 2=19w; 3=18; 2=17; 7=16; 5=15; 5=14; 6=13; 12=12

Relief Pitchers (with 25 or more saves+holds)

7>100ks; 4>90; 9>80

Assuming that you only allocate 12 spots to relievers and starter could you get by with 5 starters?

I think it would be tough, at least if you want to better than average in wins and ks. Your five starters would have to average 200ks each and your 7 relievers would have to average 80ks each. In a 16 team league with only 11 starters having greater than 200 ks and 20 relievers having 80 or more is that's hard to do. As for wins if your 7 relievers get maybe 20 wins then your starters would need to average 16 wins each. In a 16 team with only 16 starters having 16 or more wins that's pretty tough to do. Six starters appears to be more optimal though you can certainly use 5 and just not be quite as good in ws and ks.

How about the the effect on WHIP and era from using elite relievers? Well, there were 53 relievers who had 25 or more saves+holds. Of those, about 20 had around 2.5 e.r.a or lower; about 16 had eras of under 1. There were only 17>70 innings. But let's say you were able to get 6 relievers who pitched 420 innings with an era of 2.5 and a WHIP of .9 and you had 6 starters who pitched 1080 innings. What would the starters numbers be so that the overall pitching numbers would be 3.6 era and 1.2121 WHIP. The starters numbers would be 4.02 era and a 1.33 WHIP.

Don't have anything to say about starting pitching values.