Fdmatt wrote...
Previous lore as in what?
The Protheans gave them centuries of war and they lost the Citadel from the get-go per the cycle.
Shepard stopped the Citadel invasion, bought the galaxy 4 years to reverse engineer their technology, and blew up the Alpha Relay to stop them from spreading so quickly. He also gathered the largest and most diversely skilled military force ever assembled.
The Protheans were more widespread and technologically advanced than any species in the current cycle, and knew about the Reapers prior to their invasion as well. But, nothing is known about how powerful the Prothean military was, or of its capabilities, so they would be an unfair comparison.
The current cycle, however, refused to believe that the Reapers were real (only the Turians made a decent effort to reverse-engineer Reaper technology). Even Sovereign only fell in battle because his shields and weapons were knocked offline, allowing a free shot by the Alliance Navy.
It can be fair to assume that their are thousands of Reaper ships, which would probably put them on equal ground with the Organic's fleets or even be larger than them. Even if Earth was retaken conventionally, you still have the Reapers in other systems to worry about (Reapers that were able to obliterate the Batarians extremely quickly, ravage Thessia and Palaven, and devestate other worlds).