I am a little surprised you only won 4 matches out of 15. Should have been more like 5. 😜. If you listen to SMIP podcasts or if you read through the metagame details @ChubbyRain have provided, the White Eldrazi matchup vs Shops is awful. 33% is what I would expect.
The main issue is that you have to guess when sideboarding and with your opening hands. You have hands that have Null Rod and wasteland. They go tomb, Revoker Go. What do you do? They will puke out 3 more permanents with Inspector and Workshop turn 2. Nice Null Rod.
Or you get hands that STP and Kataki. They go ravager or ballista. Nice Kataki. What I am trying to say is that you have to guess what type of game you will be playing and you have to get lucky.
You need hands with Kataki AND Null Rod. Or, assuming you are on the play game 2, Thalia 2.0 is great. Actually it's almost impossible for them to beat.
One for one trading is not the way to win. Null Rod, serenity, balance, etc are ways to get ahead on cards. You have to assume whatever land you play will get wasted so you have to make an impact that will get multiple cards of theirs. I may start doing leagues again online with Eldrazi. But right now doesn't seem like the time to try to beat Shops. Unless you maindeck Kataki and Null Rod over priests and Revokers. We will see. Best of luck to you.