Complex sentence: Welles's opinion of Falstaff had intensified since first playing the part, and his new version of the play focused more upon the relationship between Falstaff and Prince Hal than on the historical story of Hal's defeat of Hotspur.
Split into simpler sentences: Welles's opinion of Falstaff had only intensified since first playing the part. This new version focused more on the relationship between Falstaff and Prince Hal than on the historical story of Hal's defeat of Hotspur.