I don't have a problem drafting two starting pitchers from the same team at all... three may be overdoing it... but to each his own.
For batters, as previously mentioned, it matters if you're playing in a head-2-head league (weekly matchups) or a roto league. If it's a weekly matchup, then it could work against you if their team matches up against another stronger team's #1-2-3 starters (ie: Boston, NYY, STL, PHI, ATL). Obviously it works the other way too... but I like to err on the side of consistency than all-or-nothing.
Good luck
