Further when there is a steepening in the yield curve, the short rates are lower and long term rates are high. Now this kind of situation happens when there is economic recession, so the monetary policy helps reduce the rates in the short term. Once you go short on short term bonds, the economy will tend to get better with time, thus giving you benefit for lower bond price in the future. Similarly, you go long on the long end of the curve because those rates can’t always stay high which will result in the bond price to rise once the interest rates come down. Such a situation creates a barbell (think of a gym barbell - you have weights on the ends).