The money was in hitting bombs, and they didn't want to risk an injury. Also, Ruth probably wasn't going to remain a top-flight pitcher anyway - even for the era, he was a low-strikeout pitcher. The Yankees would have gotten 150 mediocre innings and lost Ruth's hitting for too many games (and they had plenty of good pitching).
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Now, Ohtani has been fantastic for two and a half seasons. He doesn't have an argument to rank near the top among all players all-time, at least not yet. He does have a fantastic peak - not an unprecedented one in terms of value, but extremely high. If I had to guess, he'll end his career among the top 75 players of all time, but not the top 25. I could be wrong, but I'd not bet on him getting to the top group (primarily due to injury risk).