Star ratings - How are they decided?

This is not a post on any game specifically, but just the FM games in general. Here is what I do know.

The ratings are not always accurate. Depends on scouts/coaches JPA and JPP attributes and I also believe tactical knowledge plays a role in this too? Are there any other stats that effect the star rating estimates?

The star ratings are based on what team you are and who else is in the squad. For example last year Arsenal's star ratings took a hit as Ozil joined and he was a class above the rest. FM15 seems to have fixed that for Arsenal.

So that is what I know, there are 2/3 things that effect the ratings:

Coach/Scout

What team you are

Who else is in the team

So this leaves me with a few questions actually. For me as Arsenal a player would get a 2 star rating, but the same player at a mid table/Europa League finishing team may rate them as 3/ 3 1/2 star. I've seen this before where I have looked at a player, seen a low star rating and avoided, but someone else buys them and they do really well. I understand different team and mentality. But why if I sign these kind of players they play like 2 star players but when other teams buy them they play like 4 star players. Does that question make sense?

My main example comes from I think FM13 where Spurs would buy Jose Sosa. My scouts rated 2 1/2 stars so I never bothered, but he had the most assists and was in top 10 goals. So when I started a new game I brought him and he was terrible. What makes the difference in a player to do that?

What I am trying to say is, if at Arsenal I buy a couple of 2 star rated players to use vs teams where they would rate them 3 star or higher, why do they play like a 2 star player and not a 3 star or more? It's like youth players as well. Get them rated to 2 star and use them vs lower teams but they still look out of place. But when I play games not as Arsenal the same youth players get rated very highly by other teams.

I think I'm confusing myself now. But yeah am I right with how the stars are generated?

Stars are based on your team as a whole and to some extent the reputation of the league you play in as well as how accurate your staff are.

For instance if every member of your squad had 180CA the squad average would be 180CA and every player would be rated as 3* as they are all average when compared to the other players in your squad.

If one of those players moved to a club where the squad average was say 160CA they would be given say 4* because they are 20CA above the squad average.

How a player does on the pitch doesn't always match his star ratings for a few reasons.

A) Star rating is an overall estimate of that players skill level but on the field its attributes that matter (Both seen & hidden).

B) On the field he may be playing in a position/role that does/doesn't make the best use of his attributes.

C) One of the hidden attributes is consistency which is how often the player plays to the best of his ability.

Stars are based on your team as a whole and to some extent the reputation of the league you play in as well as how accurate your staff are.

For instance if every member of your squad had 180CA the squad average would be 180CA and every player would be rated as 3* as they are all average when compared to the other players in your squad.

If one of those players moved to a club where the squad average was say 160CA they would be given say 4* because they are 20CA above the squad average.

How a player does on the pitch doesn't always match his star ratings for a few reasons.

A) Star rating is an overall estimate of that players skill level but on the field its attributes that matter (Both seen & hidden).

B) On the field he may be playing in a position/role that does/doesn't make the best use of his attributes.

C) One of the hidden attributes is consistency which is how often the player plays to the best of his ability.

Thank you for the run down

This helps

If I scout a player on another team is his star rating rated against the players on his current team or against the players on my team.

What about when scouting a player who is not currently on any team?