I remember now the season I bought 7 strikers in the last december lol

1st- leg and height and so, don't matter, there are too much factors, maybe 15 or so, that affect the game, everyone in a slightly way, so, do it simple.

The players have visual skills. Players have then too, internal programming, with min's and max's of aggressiveness, %'s of efficience of, shooting, in 1vs1, freekiks etc, too contribution by default, what means how appear a player during a match.

So the visual quality affect slightly to the base programmed internally. And I say slighty because you can find a ST with good internal ratios, lets say that often with 5 stars score 1-3 goals per match so, in league finally score 42 goals in 26 matches, this as said with 5*, but, another, with low internal ratio, maybe, even if you train him till 9 stars or 10 he will not appear in the match so often or will score more than 8 goals in the 3 competitions.

Thats why I say that external skills have a slighly influence under the internal programming.

So, the key to find a good ST, is see the contribution he does in terms of goals/assistances during some matches.
I tend to find in the market players that have a good ratio with their old team, then if they work or not, depend of, how these players work inside your team, because you can not buy 11 players that scored 40 goals with their teams and see the same result inside your team, because the game calibrates how have to work everyone, who is the best man for corners for example, who dominates more, who is more aggressive, so these decisions that the game do are, to make you work as manager and decide to select one or another for freekicks, sub' a aggressive player etc.

Tests are the key as I said always, if you do a friendly vs a 1* team you will oversize the internal programming of your team and you will see the best players so, if you buy a ST and vs a 1* team score a hattrick, this is your boy. If, appear often and give you something, too take this into account.