Diggins skips a relay for the fouth consecutive time. Weird that FIS decided to remove the points for relays with the introduction of the new pointsystem.
This is absolutely fair and reasonable for her to do, though, especially now that the relays don't matter so much for points. A lot of her World Cup overall rivals will either skip some distance races or skip some sprints (or DNQ them) whereas Diggins tends to do the full calendar start to finish, and also will tend to get further in sprints than many of her distance rivals, as well as have to go all out in many distance races than most of those who can outscore her in sprints. Assuming equal form, she's going to be the US' best chance of victory in pretty much every single race on the calendar bar one (the Alpe Cermis stage of the Tour de Ski), so she has to have
somewhere that she can take a break, even though she seems to have very strong recovery enabling her to hold good form for longer than most.
Another factor is that unlike the skiathlon, where it seems by and large the Classic is a matter of attrition before the race is broken up in skate, in the relay the Classic legs tend to be more decisive in breaking the field up, which has often been to the US' detriment since pretty much every skier they have is stronger in skate. This has meant often Diggins is handed over to with a deficit already established, and has to go hard every relay leg to try to pull the team back into contention, to varying levels of success, whereas, say, Finland, where their best technique is Classic, get to hang near the front at the halfway stage and their skate skiers can hitch a ride on others to survive rather than having to do the whole leg alone as Diggins has all too frequently been doing in recent years. Her improved Classic in the last season or two has led to her being deployed on those legs, but with her being the team's main ace, using her weaker technique just to keep them in contact has not been any more successful in the long run because then they don't have their main trump card to play on the skate leg.