This is not what the Joneses have said. When you sign free agents from another team, it comes with a lot of uncertainty and risk. The more you invest, the bigger the risk. After the 2012 big-money signing of Brandon Carr flamed out, the Joneses decided the high-cost, early-free agency signing period was too big of a gamble. Players get paid more than they are worth and often end up not living up to the contract. So they abandoned that period almost entirely (unless they felt there was a player there who was a bargain). Other examples they used of this was Marco Rivera.
With their own free agents, they believe they better understand the value of the player. They know the player's temperament in the locker room, the amount of effort he gives and the level of play he can achieve. It isn't merely about rewarding their own, it's about risk-reward management. Although there have been failures in this strategy, they still believe it is less risky than signing other teams' FAs to exorbitant deals.
I don't happen to agree with them, but if you look at all that they have said over the years about why this is their philosophy, these are the reasons they do what they do.