If you take the ever-fluctuating world rankings as your gauge, then England will be favourites for the 2018 Six Nations, with Ireland the best-placed side to come at the kings without missing.
Both England and Ireland have developed impressive squad depth since the last World Cup, but in spite of the swelling of the reserves, both squads have a few irreplaceable players. For Ireland, the half-backs. For England, those who shone as bright as anyone on the Lions tour: Owen Farrell and Maro Itoje. (The fact the latter started just one of England's three Autumn Internationals does not undermine this, but proof that Jones is looking for further cover).
Itoje has been a barnstorming revelation since making his England debut in 2016, and has lost a single Six Nations game since his debut: against Ireland in Dublin last March.
The day has now arrived, however, in which Eddie Jones must face the prospect of planning for the competition without the formidable forward. Itoje broke his jaw in Saracens' weekend defeat to Harlequins, with scans confirming the injury today. He is expected to miss ten weeks of rugby, which would likely rule him out of the opener v Italy at the very least, and probably out of the second game against Wales.