I personally think that some injuries are just injuries, and if they are treated and rehabbed properly, they won't be much of a problem. I know from personal experience with injuries and through my job as an Army nurse that there are injuries that have lingering effects. I also think that there are some people who are just unlucky or have bad kharma and are doomed to battle injuries for their entire careers but there are few of these players.
I think that if TT and the front office should consult with their medical staff regarding prospects' injuries if they don't already. Every person is different so while a knee sprain might make one guy more susceptible to future knee injuries, the same sprain might have no lingering effects on a different player.
There are many injuries that are common to having lingering effects, so I will try to stay with the ones common to football.
Concussions- Concussions make the person more susceptible to future concussions and post-concussion syndrome. There is no argument here, this has been shown time and time again. The problem is in proper and speedy diagnosis and prompt treatment. The sooner you catch it and treat it, the better the prognosis.
Ligament tears/sprains- Sprains are either an over stretching or very slight tearing of a ligament, depending on the degree of the sprain. Partial and complete ligament tears are the next steps after a sprain. All of these injuries may have long lasting effects but the odds of this decreases in step with the severity. So a minor mcl sprain has a much smaller chance of causing future problems than a complete mcl tear. The key to preventing lingering effects of these injuries is proper treatment and rehab.
Muscle strains/ tendon tears- are similar to sprains and ligament tears but they involve muscle. Muscle is much more vascular than ligaments so the prognosis is usually better. Healing times and rehab is usually shorter too due to the faster rate of healing.
Also, alot of factors regarding injuries have to do with the players' family medical history. The players' position plays a key factor too. Positions that involve more than average contact, carry higher risks. Positions that require players to have bodies that are bigger and heavier will carry higher risks too. A lineman who is over 6'2 and over 320lbs is going to but a great deal more stress on his knees, ankles, hips, and back than a kicker, quarterback, or wideout.
I am a firm believer in that prevention of these injuries is key and that proper strength and conditioning is one of the best ways to prevent most of these injuries. A facet that is overlooked a lot however is diet. WHat these athletes put into their bodies is just as important as what they do to/with their bodies. Some seemingly harmless medications/nutritional supplements can have nasty side effects. I know some antibiotics make connective tissue more prone to ruptures/tears as a side effect. Some athletic supplements can cause sever dehydration or electrolyte imbalances. Electrolytes have a very important role in muscle function and tone.
I know that the teams' medical staff are probably very vigilant and do their jobs well. Yet if a player is taking something that isn't on the banned substance list, there is no test for it. So unless he is up front and forthcoming about this medication/substance the medical staff won't know he is taking it. This can cause serious issues.
Injuries and players being injury prone or recurring injuries is a big issue that has a lot more to it than I think most people realize. Yet any injury to connective tissue at joints can cause some types of arthritis. Chronic inflammation in a joint causes some damage and tissue breakdown making that joint more susceptible to future injuries. Because arthritis is not a curable condition, all we can do is treat the symptoms. THis can help reduce the additional risks but not eliminate them.
The bottom line is if players, coaches, and the medical staff need to all be on the same page. There needs to be open communication and proper strength/conditioning done, even in the off season. This will minimize injuries. Yet once a player gets hurt, because injuries are part of the game, that player needs to be diagnosed and treated ASAP. He then needs proper rehab. I think teams, especially ownership are probably a little too aggressive with rehab. Its bad business to pay a player who isn't playing. I know that sounds cruel but I don't buy for an instant that a guy like Jerry Jones would care about his players long term health. So I am sure that rehab is usually a bit more aggressive than it should be, in order to get the players back on the field as soon as possible. I'm sure the competitive nature of players can factor into this as well.
Healing is a delicate process that is different for every person and it should be treated as such.