Tech's the only reason why markets are down to start Tuesday's session, says Charles Schwab's Joe Mazzola. He explains how the heavy-weighted sector serves as a double-edged sword in price action. As for the earnings season so far, Joe says it's interesting how misses aren't punished as much as last quarter. He tells investors to watch AMD Inc.'s (AMD) after-hours print to see if it can continue add muscle to the AI hardware play.