What is the length of a baseball career?

Keep in mind that the decision to go pro directly from HS is not necessarily the players---he has to be drafted or signed as a free agent.

I would same the average baseball career college and pro is somewhere in the 10 year range ( 4 college/6 pro)

FWIW, my son's agent told me the average time a player spends in MLB is only 4 years, remember that is average, not including the years it takes to get there.
To try to answer your question, HS players (unless they are the Rick Porcello type) are estimated to be ready within 4-6 years for MLB and that also depends on whether you are needed and all teams are different. They can be released at any time just like any player. Is there an advantage to going early, all depends on the player, his potential and how much time the team is willing to give each individual player and most likely how much of an investment the team has made.
As we know there are many (example David Price) college players who are ready to enter the game on the MLB level after they are drafted out of college.
Reaching the majors is about the level of talent one has, and most HS players drafted very early have what it takes to get to MLB, so that is a tough question to answer because everyone of them is different and a lot has to do with maturity both physically and mentally and staying healthy.
Age matters, the older you get and haven't moved ahead, the sooner you will be released. 18 years olds grown on the farm should be ready by their rule 5 draft year (6 years), college players should be ready sooner (5 years),unless injured so a HS player gets more time to develop in the system than the older college guy.
Each level in milb age driven, for example a 19 year old in low A is on track but a 25 year old maybe too old. So who has the advantage?

Remember there is a draft each year and that means each year a turnover in players, it's not a forever thing for HS players or college players.

I am not sure if it answered your question. I am not sure you can exactly measure average time, all players are different and their situations are different.

I think that I understand what TR is saying, some people try to figure out all of this stuff, but the player has to be drafted or signed first for any of it to happen.

My advice, whatever is happening in the fall for many players means nothing until they show themsleves in the spring, if you have a player of HS age that might be drafted, try to relax , stop calculating, trying to figure out things and enjoy this time, it will be over before you know it.

Actually, the question/answer is not for me or mine.

And, by definition, the gate keepers are the mlb clubs (without being drafted, nothing to decide!).

But, while enjoying the time left in hs, one can continue to think about the future potential forks in the road. (The time went by so fast during several year recruiting period to college; I am certain it will fly by as fast over the next 8 months -- so best to be thinking about an uncertain possibility.)

I have found research which indicated that the average length of a mlb career is 5.6 yrs (that is the length of time for all position players and does not include pitchers (which makes the study pretty much worthless to me)).

And, of course, each player is an individual case who advances through the system according to his own merit and his club's needs.

But, what is the median (median is probably a better measure) time of a college+pro baseball career (or a pro only career)?

My gut feeling (which is worthless in trying to form a truly educated opinion) is that there is no real hard answer; that the variables are too many and the individuality of each players' career cannot be boiled down to a meaningful group statistic.

But I thought I'd ask and value all input.

The 5.6 has no value without factoring in pitchers, who have ashoreter life span in MLB than position players.
I agree, there is no way to try to factor the question asked there are too many variables, as too many players that come from all different time frames in college (also due to redshirt).