This article is part of our Fantasy Baseball Injury Report series.
The first full week of the 2021 MLB season is in the books and injuries are already beginning to pile up. The majority of the injuries appear to be soft tissue injuries, meaning they involve muscle, tendons or ligaments. Even if these strains and sprains are mild, the possibility of a cascade injury or subsequent reinjury or aggravation will linger. Furthermore, other neighboring areas may also become vulnerable to injury.
To better explain this concept, I often refer to the kinetic link model. The model is utilized by medical professionals as a way to see the relationship among injuries. The body is imagined as a connected arrangement of links working together to carry out a desired action. If an injury occurs somewhere along the chain, the other parts are inherently affected. For example, the kinetic chain is often referenced when discussing the throwing arm of a pitcher. In these cases, the arm is the kinetic chain with each joint of the arm (shoulder, elbow, wrist) serving as the individual links in the chain. If one of these links is weakened or compromised due to injury, the strength and ability of the entire chain is altered as the other links assume larger amounts of stress to withstand the change. Even a mild strain or sprain can increase the player's risk of suffering another injury to muscles or ligaments in a different location of the chain. For pitchers, this is often seen in the muscles of the forearm and the ulnar collateral ligament
The first full week of the 2021 MLB season is in the books and injuries are already beginning to pile up. The majority of the injuries appear to be soft tissue injuries, meaning they involve muscle, tendons or ligaments. Even if these strains and sprains are mild, the possibility of a cascade injury or subsequent reinjury or aggravation will linger. Furthermore, other neighboring areas may also become vulnerable to injury.
To better explain this concept, I often refer to the kinetic link model. The model is utilized by medical professionals as a way to see the relationship among injuries. The body is imagined as a connected arrangement of links working together to carry out a desired action. If an injury occurs somewhere along the chain, the other parts are inherently affected. For example, the kinetic chain is often referenced when discussing the throwing arm of a pitcher. In these cases, the arm is the kinetic chain with each joint of the arm (shoulder, elbow, wrist) serving as the individual links in the chain. If one of these links is weakened or compromised due to injury, the strength and ability of the entire chain is altered as the other links assume larger amounts of stress to withstand the change. Even a mild strain or sprain can increase the player's risk of suffering another injury to muscles or ligaments in a different location of the chain. For pitchers, this is often seen in the muscles of the forearm and the ulnar collateral ligament (UCL) of the elbow. A strain of the any of the muscles in the flexor bundle can divert undue stress onto the ligament and lead to a significant sprain and vice versa. Earlier this week Mariners pitcher James Paxton was diagnosed with a forearm strain before it was also determined he would need to undergo Tommy John to repair a torn UCL. His season ends after just 24 total pitches.
The same holds true for the lower extremities where strains of the muscles of the hip, knee and ankle, including the hamstring and calves, can negatively impact the entire kinetic chain. This is the reasoning behind my concern for Josh Donaldson's early season hamstring strain. Yes, he's progressed nicely in his recovery and is likely to be activated in the coming days. However, Donaldson has a lengthy history of lower extremity strains, making him a risky play moving forward.
Bellinger's calf contusion was significant enough that the Dodgers opted to place the outfielder on the injured list. While not a strain, the injury still impacts the kinetic chain in a similar way. The Los Angeles medical staff is keenly aware of the risk of rushing recovery and has opted for a conservative approach with Bellinger's recovery. The move was backdated, and he remains eligible to return on April 16. However, Bellinger was limited to light agility drills over the weekend and will need to show considerable signs of improvement to hit that potential date.
Marte suffered a strained right hamstring while running to first and has already been sent to the 10-day IL. Fortunately, Marte does not have a length history of lower extremity strains, and the injury does sounds like a low-grade, mild strain. However, it seems likely he sits beyond the minimum 10 days given his position and style of play. Tim Locastro will man centerfield for the Diamondbacks and could be a nice fill-in, especially for teams in need of stolen base help.
The Padres outfielder will not undergo surgery for his shoulder injury and will instead spend time rehabbing the area in an attempt to play out this season. Tatis will focus on improving the strength of the muscles surrounding the shoulder to help offset the instability caused by the "slight" tear in his labrum. He's already begun doing some light fielding work, and the team appears optimistic he will return when first eligible. Still, I don't think this is the last time we hear about the shoulder, as offseason surgery seems inevitable. However, it does appear as though the emerging superstar is going to try everything possible to make it through this season. The risk here is high but so too is the reward.
Check Swings
A.J. Puk: The A's have placed Puk on the IL with a strained biceps on his throwing arm. The biceps is a two-joint muscle, meaning it influences both the shoulder and elbow. As a result, extra care must be given for pitchers to protect their arm. Oakland is keenly aware and has already stated he will miss more than the allotted 10 days. Remember Puk is just seven months removed from a debridement surgery on his labrum and rotator cuff, and the A's will likely manage his recovery with extreme caution.
Trevor Rosenthal: While the length of Puk's absence remains a bit uncertain, Oakland knows Rosenthal will miss an extended period of time after undergoing surgery for thoracic outlet syndrome (TOS). TOS occurs when nerves and/or blood vessels become compressed in the shoulder. The compression of these structures can lead to numbness, tingling and weakness of the shoulder and arm, and can carry over into the back. Surgery is often used to address the source of the compression. Rosenthal's issues appear to involve his first rib, which has since been removed. Furthermore, multiple muscles of his chest and neck were also cleaned up, likely to address lingering scar tissue. Rosenthal will be reevaluated in eight weeks and has already been placed on the 60-day IL. His recovery is likely to extend beyond the 60 days. Sergio Romo and Jake Diekman will move up the depth chart and get the first crack at closing out games.
George Springer: On the plus side, the strained oblique that sidelined Springer to start the year appears to have fully healed. Unfortunately, the Blue Jays slugger will remain shelved due to a strained quadriceps muscle sustained during the final stage of the recovery process. The strain is being described as a low-grade injury, but he remains without a return date.
Mookie Betts and Christian Yelich: The two former MVPs have both missed time with ailing lower backs. Betts has missed four consecutive games with what is being described as lower back tightness, while Yelich did not play on Monday. Tightness is often linked to a muscle-related issue though neither player has been diagnosed with a strain as of yet. Consider them both day-to-day for now.
