Not missed in the lineup? Andrus would have been a pretty huge upgrade at SS from 2010 through most of 2012 when were trotting Alex Gonzalez or the ghost of Yunel's Braves career out there. Harrison would have been a huge help in 2011 and 2012. Feliz was one of the most dynamic relief pitchers in baseball from 2009-2011, mild understatement to say he could have been useful.
If we don't make the Tex trade and keep those players then it's almost certain that we make the playoffs in 2011 rather than missing them by a single game (having Andrus over Gonzalez alone would have seen to that). Our SS combined for zero WAR in 2012, Andrus had 4 WAR himself, and Harrison was worth slightly over 6 WAR in 2012. So with Harrison and Andrus in 2012 there is a decent chance we would have been able to catch and pass the Nats, allowing us to not get bounced in a one game WC playoff.
Who the heck knows how far we go if we made it past the playin stage either year, but we would have had a chance. The Tex trade made a huge impact on those years, acting like those players wouldn't have mattered is revisionist history and quite absurd IMO.