CNBC's Bob Pisani spoke with Kim Arthur, CEO of Main Management, Wes Crill, Head of Investment Strategists and Vice President at Dimensional Fund Advisors and Dave Nadig, Director of Research at ETF Trends. They discussed sector rotation in full swing this year and the big debate over market timing; does it work and what are some of the biggest pitfalls and perils? In the 'markets 102' portion of the podcast, Bob continues the conversation about marking timing with Wes Crill from Dimentional Fund Advisors.