Youth Squad and Players
You can acquire a new player each week by moving a youth squad player up into the senior squad. The better the youth squad activities are, the better the chances of the youth squad player succeeding. You don't have any choice in what kind of youth squad player you'll get, apart from choosing between a goalkeeper or an outfield player. Don't count on receiving top-notch players each week. Most youth squad players you try out won't qualify for your team, or be good enough to sell to other managers. If you have one or two of them per season either moving directly up into the team, or able to be sold, you should be satisfied - think about how things work in reality!
Many clubs put a lot of money into their youth squad, but there are also those who spend less money or none at all, buying reinforcements from the transfer lists instead. However, if you do decide to build up your youth squad structure, be prepared that it might take some time before your investment pays off with reasonably able youth squad pulls. You may find there's little point in moving youth squad players up if your youth squad status is "poor", for instance.
Every week you're allowed to make a large (€20 000), medium (€10 000), or small (€5 000) investment in your youth squad. The effect of these levels of investment can be seen on the Youth Squad Improvements page. If you don't change the amount, the amount invested the previous week will be drawn from your bank balance after the next weekly economic update.
You're only able to promote one youth squad player per week. Every time you promote a youth squad player, it will cost the club €2 000. If you are lucky, the Youth Pull will then be able to join your team, or be sold.
Information on your youth squad activities can be found in the "Your club" menu, under "The Club" caption. This is also where you enter the amount of money you want invested into the youth squad, and where you move them up from, each week.
A theory is that the distribution of each skill of a youth pull is an exponential (or a Poisson, if we prefer to remain into discrete distributions), with the level of the youth setup influencing the parameter of the exponential distribution.
Another theory is to pull Goalkeepers whilst your youth squad is lower than solid. The reason behind this is that only one skill is ever relevant, rather than all seven. A passable keeper will usually sell, whilst a outfielder with passable stamina, and 6 poor skills will not.
Plumbers and Golfers
Shockingly, even excellent youth squads may produce, week by week, suprisingly pathetic youth pulls. Many managers complain about their youth squad investment, decrying the level of players they pull as a waste of money, time, effort, and hopes. Even most inadequate youth pulls (17 year old goalkeepers or multiskilled players are an exception) are usually sent directly to the golf course or the local pub to spend the rest of their adult lives as misrable losers. The luckier ones end up chasing young blondes around said pub.
However, not all of Hattrick's drop-outs turn to become lazy bums. Many disastrous players have foreseen the future failure and prepared an altenative job. These players TSI sum usually does not mount much above 40, and most (And not very rarely all) of their skills hits "wretched" at most. These players are called by the HT-players by their possible alternative jobs - Plumbers, Carpenters, Politicians and so forth...