I have players, offensive and defensive linemen, that have completely maxed out their skills at their position. If I want my RDE to up his skills at LDE, I'd need to actually change his position to LDE for Training Camp, and the change it back to RDE once pre-season starts? And I can leave him as an RDE on the depth chart so I don't have to remember where he started?

If I have an LT who cross-trains as LG, is there any risk involved in that messing up any of his abilities as a Tackle? I know I've read that moving players aroumd can affect weight and speed.

Good Question llama. I too want to know.
This is what I have fanagled so far. All my own crazy, haha.
Only change the players actual position if it is permanent.
I cross position a lot in preseason (blanket, lets run the DB) - especially with late round pix, and as needed during season from injuries.
I have not seen cross-positioning impact the core pos rating, however logic would dictate the less a player plays in his true position, the less progress will be made.
All that said, I have yet to see players I spot play increase in a 2nd or 3rd position rating on my rosters. I have seen player cards in FA and other teams that prove they do, but they are definitely average joes that are good situational players, and none of the positions are fully rated.
As far as the lines go, I have had zero issues swapping and bopping when I need to.
I have not seen a rating decline in prime aged players in cross-positioning, but I would bet routine cross positioning or OOP would impact hitting max attributes and rating. Also may impact the rate of declining progress when that hits for the player due to age etc.

Very curious if any one else has thoughts and ideas.

i always thought that the player gets cross training at other positions if he has other positions and it would make sense when people have a RB at WR and RB or a WR at RB and WR where that player gets cross training at both of his positions .

Camp and mid week spins (practice) develop the positional experience for the position assigned. (Exp. LDE 78/84) Where he plays in the game, doesn't matter qb, db , or etc. , will develop that particular positional experience even though it technically not his assigned position. (Exp. RDE 38/82) .

For the game it all about snap counts, intelligence, and coaches ratings . ..mid week spins it's the assigned position, intelligence , and coaches ratings.

The trending of a player's weight, in pounds, will effect his speed and strength . So , in general this whole thing is a preference of stlye of play for the user. My schemes allow for alot of subs to play OOP, so I will switch anyone anywhere almost at any time, but generally I stay within 25 pounds of my desired goal weight (in pounds) as I like guys playing at certain speeds or strengths for certain positions .

Outside of that switchin a db to dline when the player is going to get a big speed hit at yr 9 usually works out for me to prevent early retirement . As that is random but tied to the assigned position . Most likely he spends time playing LB as I see how his weight trends .

Another weird one is I will switch an aging TE to C just to lengthen his career , and I will switch him back to TE for the season . Then switch him back to C for the end of season spin just to avoid retirement . Tedious , but one te I had still has 77 speed at yr 13, but I swear he looked alot slower .

That trending of weight is built into the player generation so some guys will trend fast and other slower which kinda puts a cap on how far they can go. Which puts a limit on who I switch or play some places

Also, if you play an assigned LG at LT he will never max his positionAL experience at LT. It's stays 3 or 4 points lower than the max no matter snap counts , intelligence or coaches. So once again that's another user preference for me.

I do systematic cross training during preseasons. I only switch for TC if its a permanent move.

My keys for the preseason:
All players are entered in the depth chart at EVERY position where they have a future rating higher than 60 by my weights.
Depth chart gets ordered by future rating instead of current.
Overrides get cleared out. Everyone plays based on listed positions and fatigue.
Any player who is within 2 points of topping out at their listed position (or 5 points at a backup position), moves to the bottom of the depth chart at the topped-out position, and their listed position is changed to the position I am most interested in training.
I watch out here in the years where speed takes a hit. If a player is aging, I won't change him to a position where he gains weight, unless the change is permanent ... because he won't get all his speed back when he goes back to the original position for the regular season.
I pay attention to my position coaches' skills, specifically which skills they train at that position. Young WRs will very often suit up at backfield or TE for preseason, because they train additional skills there (BT and blocking). I like my skilled starters to be able throw a block downfield or during an OR. It can get me a bunch of extra yards, especially if the ball carrier has good BT.
Fatigue is set by position, and based on the number of players available to cross-train. If I have a half dozen or more players cross-training at one position, it might be set in the low 20s.

I expect to lose every preseason game until I've been team-building for 3-4 seasons. If I just took over a junk team, I might extend this regime into the first regular season for a few choice players. Team-building is not the same as tanking.

It's a lot of work fiddling the depth charts, but I wind up with guys like this:

https://cust35.myfootballnow.com/player/6572
Vandiver can play anywhere I need him on the O-line. One-man depth.
or this:
https://cust35.myfootballnow.com/player/7138
Skinner started as a CB, moved to Safety as he aged and lost speed, and is now useful as an OLB (where he can play until he retires), but he can still cover the slot or play deep if I need him there.
or this:
https://cust35.myfootballnow.com/player/8262
Chandler isn't a speed demon, but he is a swiss-army knife. He plays very well at backfield or TE, and is still young enough to improve at slot receiver.

Tarq is my MFN doppleganger, apparently.. My only diff is I deactivate max rated or near maxes that would be starters until the last preseason game. This method also requires using the substitution rate for pre in the misc game plan tab with the understanding of starting rooks and 2,3,4th strings. I do a full reverse, 3 quarters 1st 2 games, then 2, then flip to what I hope to start season depth wise, and go 1-2 1/4s depending on well, what ever squeezed into my head that day lol. Usually 1. Hate to injure starters before any real game is played for some positions.
I did not think to also tweak fatigue in positions with a bucketfull of players in the pre, gonna give it a whirl this pre. Good info gang, hope to hear more.

Some great info there Tarq thanks - I've never consider using pre-season that way but certainly will in future.