At various points this season, Daniel Agger's either been not strong enough in the air, not strong enough on the ball, not as good as Martin Skrtel, not as good as Mamadou Sakho, and generally just not very good anymore. Some of the criticism has been valid at times, except for most of the starts he's earned since returning from injury in 2014, and those other times that he was fit this season and mostly solid. Sometimes when reality gets in the way of narrative it's better to just stick with narrative, and Daniel Agger's a player in decline.
So conveniently enough the Danish defender suffered an injury in training in the days leading up to tomorrow's match (per The Times and thus behind a paywall); apparently the injury isn't serious enough to rule Agger out for sure, but doubts about his fitness combines with some strange twisted version of reality to pave the way for Sakho's first start since the loss at Stamford Bridge during the festive period.
Plenty were prepared--myself included, trying to guess Brendan Rodgers' thinking--for Sakho to possibly come into the side, especially given Sam Allardyce and West Ham's preferred approach. Andy Carroll will be the target man in the middle with runners coming in from behind, and having Sakho's physical presence to cope with the former Liverpool forward would ideally help to stifle some of the host's potency going forward. Support from the midfield will be just as, if not more, important in that regard, but there's nothing for Carroll to knock down if the cross is defended successfully.
Sakho possibly adding strength doesn't suddenly mean that Agger would get trampled in the event he does start, however; the Swansea match aside (and a foot race with Roberto Soldado), Agger's been tremendous in nearly all facets of the game. Mamadou Sakho is excellent in the air. Daniel Agger's no slouch, though, and the partnership between he and Skrtel has been so effective that it's not worth breaking up unless fitness demands it.
Or narrative. Whichever you prefer.
**HT to the insatiable NCNole for the heads-up**