EatChildren
Currently polling second in Australia's federal election (first in the Gold Coast), this feral may one day be your Bogan King.
Nobody really knows what happened in ME2 with the whole deal as if I remember correctly Drew is credited as a lead writer in the credits for ME2. All that can really be said is that Drew stepped down from lead in ME2 but definitely worked on the game to some extent.
Walters wrote Wrex and Garrus in ME1 I believe. He wrote Aria and TIM in ME2. He also wrote Garrus's mission and story arc in ME2. Weekes wrote Garrus's dialogue on the Normandy. In ME3 he wrote the intro level, most of TIM's dialogue, Vega, and the final ending segment.
If anything, ME2 is a good example of a game that had a larger scope than BioWare could deliver. Based on the numerous recorded and cut dialogue encounters, I figure they wanted more freedom on who you could recruit and where. Somewhere along the lines they realised this wasn't working, or they didn't have enough time, and had to reel it in, segmenting the game into 'acts' defined by each Collector related mission. Hence why the main story's plot feels quite...empty.
If Walters wrote what you say, then I feel he is a much more competent writer when he's doing what the rest of the team does: writing individual characters and specific story arcs that exist outside of the core narrative.
That's where he seems to lose the plot (literally): delivering an entire game's worth of narrative. Both the intro and the end were the weakest, most rushed and plot hole riddled points of the game.