The formulas used for the tops are adapted from the LA-Loko ones.
LA-Loko is well-know in hattrick for his interesting abc of tactics, and his impressive achievements.

Lokomotiv Lund (9952)
Country: Sverige
Region: Skåne
Owner: Robin Gustafsson
Alias: LA-Loko

Here are the different formulas...

All players
The overall - the most important value - is calculated in the same way for all types of players:
{overall} = {skills} * (0.94 + {experience} * 0.01)
{stamina} maximum value is 8.
α| alpha: stamina linked with playmaking.
{α} = 0.22 + 0.13 * {stamina}
β| beta: stamina linked with any other ability (except from goalkeeping).
{β} = 0.7 + 0.05 * {stamina}
γ| gamma : stamina linked goalkeeping, 1 until HTs decision.
{γ} = 1

gK| goalKeeper
{skills} = 0.75 * {goalkeeping} * {γ} + 0.25 * {defending} * {β}

cD| centralDefender, normal
{skills} = 0.15 * {playmaking} * {α} + (0.7 * {defending} + 0.15 * {passing}) * {β}

cD| centralDefender, offensive
{skills} = 0.3 * {playmaking} * {α} + (0.6 * {defending} + 0.1 * {passing}) * {β}

wB| wingBack, normal
{skills} = 0.1 * {playmaking} * {α} + (0.6 * {defending} + 0.3 * {winger}) * {β}

wB| wingBack, offensive
{skills} = 0.15 * {playmaking} * {α} + (0.5 * {defending} + 0.35 * {winger}) * {β}

iM| innerMidfielder, defensive
{skills} = 0.65 * {playmaking} * {α} + (0.25 * {defending} + 0.1 * {passing}) * {β}

iM| innerMidfielder, normal
{skills} = 0.7 * {playmaking} * {α} + (0.15 * {defending} + 0.15 * {passing}) * {β}

iM| innerMidfielder, offensive
{skills} = 0.65 * {playmaking} * {α} + (0.1 * {defending} + 0.25 * {passing}) * {β}

Wg| Winger, towards middle
{skills} = 0.35 * {playmaking} * {α} + (0.35 * {winger} + 0.15 * {passing} + 0.15 * {defending}) * {β}

Wg| Winger, normal
{skills} = 0.2 * {playmaking} * {α} + (0.5 * {winger} + 0.2 * {passing} + 0.1 * {defending}) * {β}

Wg| Winger, offensive
{skills} = 0.1 * {playmaking} * {α} + (0.6 * {winger} + 0.3 * {passing}) * {β}

Fw| Forward, defensive
If Technical : {skills} = 0.5 * {playmaking} * {α} + (0.3 * {passing} + 0.3 * {scoring}) * {β}
Otherwise : {skills} = 0.5 * {playmaking} * {α} + (0.2 * {passing} + 0.3 * {scoring}) * {β}

Fw| Forward, towards wing
{skills} = (0.4 * {scoring} + 0.2 * {passing} + 0.4 * {winger}) * {β}

Fw| Forward, normal
{skills} = (0.7 * {scoring} + 0.2 * {passing} + 0.1 * {winger}) * {β}