MLB is my primary gig so I have a lot of strategies that I dont really wanna give up...... but here is one I used to use when I could count on a liquid in-game market (like on Betfair or Bet365). Find a highly regarded starting pitcher that tends to struggle in the first or second inning. Most pre-game lines are very heavily weighted towards the team throwing up the best starter...... but if the favored starter gives up a couple of runs in the first or second inning the odds will likely turn upside down for a while.
Take the underdog on the pre-game and then take the pre-game favorite in-game if the favored starter gives up some early runs. If the starter does not give up early runs you still have a bet on the underdog which is typically where the pre-game value is anyway.
For example say the underdog is pre-game at +225 and you take $100 units.
After the second inning lets say the favored starter has given up two runs and now the pre-game favorite is at +150. So you play the pre-game favorite at +150 for $130 units.
Now no matter what the outcome at this point you have locked in a $95 unit profit.
If after the early innings the starter did not give up any runs you still have the original underdog at +225 which only has to hit 1/3 of the time to have a positive EV.
Forgive me if I made a mistake in my example as I have not done this one in a while (since I moved to the US) but I used to have some good results with it back then.